Sterling Silver, Rhodium Plating, and Ring Sizing

What Exactly is Sterling Silver?

Since pure silver, also known as "fine silver",  is much too soft to be used in rings and other jewelry, an alloy is mixed with the metal to harden it.  Usually this is copper.  The result is a beautiful and sturdy metal that has the beauty of Fine Silver, but is now Sterling Silver.   By law, a piece that is sold as Sterling Silver will be 92.5% pure silver plus 7.5% copper, and will then be stamped ".925" or "S925" or "Sterling Silver".  Only actual Sterling Silver will bear the ".925" Sterling stamp. It is illegal under title 15, chapter 8 of the Code of Federal Regulations to in any way represent an item as sterling if it is not.

Other metals can be used in place of copper as an alloy.  These other alloys are used to help eliminate tarnish.  These metals include zinc, platinum and germaium (known as "Argentium Sterling Silver"), and even silicon and boron.

Is there a difference between Sterling Silver from Tiffany's and Other Stores?

No.  All Sterling Silver is 92.5% fine silver plus 7.5% alloy.  The metal is the same, 92.5% fine silver plus an alloy.  The difference is only in the design of the piece.

Does Sterling Silver Tarnish? What about Fine Silver?

Chemically, pure silver is not very reactive—it does not react with oxygen or water at ordinary temperatures, so does not easily form a silver oxide, which we see as tarnish. However, it is attacked by common components of atmospheric pollution---silver sulfide forms as a black tarnish while exposed to airborne compounds of sulfur (byproducts of the burning of fossil fuels and some industrial processes), and low-level ozone reacts to form silver oxide.  With Sterling Silver, the problem of corrosion or tarnishing increases because other metals in the alloy, usually copper, may react with oxygen in the air.

Sources of sulphur, which cause tarnishing,  include sweat, wool, carpeting, felt, eggs, leather, latex, and various other sources, so limiting exposure to them can help. Avoid bleach or chlorine---even the fumes will cause tarnishing.  Storing your silver in an airtight container with activated charcoal or commercial anti-tarnish strips is a good way to prevent tarnish when storing your jewelry. 

Tarnish begins as a yellow tinge to the metal, and becomes darker until it eventually is black.

To clean tarnish off of Sterling jewelry, a swipe with a treated jewelry cloth for Sterling Silver will remove most tarnish.  Sometimes a quick dip in jewelry cleaner liquid will remove tarnish from intricate silver work, but always immediately wash the piece off in warm water with a little dish soap, and dry with a soft cloth.  Do not use the liquid cleaner on jewelry with pearls, coral, or other gemstones!

Why is Sterling Silver sometimes Rhodium Plated?

Rhodium, which is a very hard (and brittle) metal in the Platinum group of precious metals, is electroplated onto Sterling Silver for a few reasons:  it helps prevent tarnishing, it helps prevent corrosion, it protects the silver from scratching or marring; it gives a very bright and shiny finish; and gives the sterling the look of white gold.  Why? Because white gold is gold mixed with alloys, but is still slightly yellow.  Plating white gold with Rhodium gives the bright, shiny, platinum look that is desired in white gold jewelry.

Rhodium is plated onto sterling silver rings for durability as well as beauty.

Sometimes the layer of Rhodium on jewelry is quite thick, but often the Rhodium layer is an extremely thin layer of metal that is electroplated over the silver or gold.  It will eventually wear off.  Rhodium plated rings especially will need to be replated after several years of wear.

►► CAN I RESIZE MY RHODIUM PLATED STERLING SILVER RING?◄◄

Certainly, it CAN be resized, but should it be?  The short answer is NO, I don't recommend that.  There are several reasons why.  First, in order to plate Rhodium over Sterling Silver, another metal or two must be plated onto the Sterling so the Rhodium adheres, and without contaminating the Rhodium solution.  There are three methods to plate silver:

     1.  First Copper, then Nickel,  then Rhodium.  (This is most common)
     2.  First Palladium, then Rhodium.
     3.  Rhodium straight onto Sterling Silver.

The first two are done in that order because the Rhodium solution is sensitive to copper and will loose its bright plating ability if it is contaminated by base metals, especially copper. 
If one plates straight onto Sterling Silver, then copper in the silver alloy will, after a short time, degrade the solution and the plating will be dark.

Additionally, the Rhodium layer is very hard and brittle, and cutting the band will possibly result in the shattering of the Rhodium layer, revealing the nickel or copper layer underneath.  A skilled silversmith (NOT the jeweler at the mall) can successfully cut through the band and adjust the size and replate the ring---but this can be costly and can also undermine the integrity of the original ring.

A skilled jeweler or preferably a silversmith might be able to "stretch" the ring slightly using a mandrel, but that depends on the thickness of the band and the setting itself, and would need to be discussed with your jeweler first.

Why can't a jeweler use a laser or heat the band?

Different metals melt at different temperatures.  Rhodium, on the outside of a ring band, is an incredibly hard metal, with one of the highest melting points of all metals.  Copper or nickel, plated between the Rhodium and the Sterling Silver, is much softer, although harder than Sterling.  Sterling Silver is an alloy of soft silver and copper.  The melting points of these metals are:

             Rhodium...................3571 °F
             Copper.....................1981 °F
             Nickel...................... 2651 °F
             Sterling Silver............1651 °F

If Rhodium were heated to the point where it would melt or even soften to cut, the underlying metals would all liquify.  If done by an inexperienced person, this would create a mess, and probably ruin the ring.

Is there a way to test metal to see if it's Sterling Silver? 
Yes:
(1)  First, does it have the "925" or "Sterling" marks somewhere?   If it does, then it is sterling silver.  Sometimes Sterling Silver isn't marked, or the markings have worn off.  Often, vintage pieces and Native American jewelry is also not marked.  Clean your piece to remove any tarnish or dirt and inspect it carefully for any hallmarks or maker's marks.
(2) Then check:  Is it magnetic?  Sterling Silver contains no metals that would be attracted to a magnet, so if it is, it's probably Stainless Steel or some other metal.  Use a strong Neodymium magnet.
(3)  Next, if it's not Rhodium plated, you can try purchasing a test kit.  A small scratch can be made in an inconspicuous spot and a drop of Nitric Acid applied.  This will ruin the ring, so often the metal is rubbed onto a "touchstone" and the Nitric Acid is applied to that touchstone rubbing.  You will have to analyze the color that appears as the acid sinks into the piece. Be sure to follow the instructions and color scale of your specific silver test. In general, the color scale is as follows:

• Bright Red: Fine Silver
• Darker Red: 925 Silver
• Brown : 800 Silver
• Green : 500 Silver
• Yellow: Lead or Tin
• Dark brown: Brass
• Blue: Nickel

(4) A less invasive method and quite simple is the "bleach test".  Silver tarnishes extremely quickly when exposed to bleach (or ammonia, but that takes longer).  Simply place a drop of bleach on your item and if it quickly turns black, that is tarnish and the piece is silver.  You can then polish the piece and remove the tarnish.
(5) Take it to a professional--a reputable jeweler, a silversmith, an appraiser--who can determine if it's sterling silver, and maybe give more information about any maker's marks or hallmarks on the piece, and its value.
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I would recommend that if you are buying a ring, such as a vintage ring, that is Rhodium plated, buy the ring in the proper size!  Don't expect to take any ring that has been Rhodium plated to a jeweler to size it.  The results will most likely not be good, or even disastrous. 

Gemstone ❤ ZIRCON v. Cubic Zirconia

Clear Zircon

Zircon is a mineral, a naturally-occurring gemstone.  It's a beautiful gemstone and doesn't get a lot of "love" from the public because people are often confused by the name Zircon---it is very close to "Cubic Zirconia" or CZ, which is a man-made stone.  They both contain the element Zirconium, but Zircon is naturally-occurring and a CZ is made in a lab.  Very confusing!

The colorless variety of Zircon is the natural element that most resembles diamonds.  Zircon also has a wonderful refraction which gives the gemstone lots of fire.  It can also seem to have more than one color.  This effect is called pleochroism.  It has a Mohs hardness of 6.5, and its strong luster and intense fire makes it a very beautiful NATURAL alternative to a Diamond.  (Please note: Moissanite is NOT a natural mineral, but is created in a lab, as is Cubic Zirconia.)

White Zircon

The word Zircon comes from the Persian word "zirgun" which means "gold", which makes sense since the majority of Zircons are a brownish gold color.  Zircon is associated with granite.  It's made of Zirconium Silicate.

Blue Zircon

Zircon is found in a variety of colors:  white, colorless, blue, green, red, yellow, orange, brown, pink, purple, grey, and black.  Blue and clear zircon are used the most in jewelry and are heat treated.  Heating the Zircon will increase its transparency, and change colors.  Heating brown or grey zircon in an oxygen-free environment will yield blue gemstones.  Heating them in an environment with oxygen yields a golden brown transparent color.  Almost all blue and colorless zircon are heat treated.

Trade Names:

- Starlight:  a blue gem variety of Zircon; heated
- Matura Diamond:  trade name for colorless Zircon
- Jargon - colorless, pale grey or pale yellow Zircon
- Jacinth - yellow, orange, brown or red Zircon; name goes back to Biblical times.
- Seiland Zircon - dark red Zircon from Norway

Red Zircon

Where is it found?

Cambodia, Burma, Sri Lanka, Australia, Mozambique, Tanzania, Madagascar, Nigeria, Pakistan, Afghanistan, Italy, France, Germany, Russia, Canada, United States

Similar Gemstones:

Colorless - resembles Diamonds, and also CZ.  It is distinguishable by its hardness and double refraction.
Blue - resembles Blue Topaz, Aquamarine, Blue Spinel, Tourmaline, Apatite
Golden Brown - resembles Topaz, Citrine, Sapphire, Garnet
Yellow - resembles Heliodor (Golden Beryl), Sapphire, Canary Diamond, Chrysoberyl, Topaz
Pink Zircon - resembles Topaz, Morganite, Kunzite, Spinel, and Rose Quartz

Golden Yellow Zircon

The luster, fire, hardness, and double refraction make Zircon distinguishable from other gemstones.

OPALITE: Not a Gemstone! Not Dolomite or Quartz! It's GLASS

Opalite - GLASS

I'm constantly amazed at the "creativity" of online sellers, and that includes wholesale companies in China and Thailand and all over the world, and sellers on Etsy and Ebay and other online sites.  Too bad this creativity is used to scam buyers---it hurts everyone, from honest sellers to naive buyers.


Opalite is a beautiful "stone" that can be purchased all over, and Michael's (the crafts supply store) has a LOT of it.  It's clearly marked on their tags as "Opalite GLASS" because that's what it is---it's GLASS.  It's very inexpensive (about $5 a strand not on sale).  It's not a gemstone, not made from other gemstones, or any mineral.  It is a glass product.  It is a beautiful glass, but glass nontheless.  I wrote about Opalite last year (HERE) because I was seeing it being sold as "Moonstone" or "Opal" which is a terrible thing to do---it's not any sort of gemstone!  I explained how and where it's made in that blog post.

In my Etsy feed today, I saw an object for sale called "Opalite Gemstone".  In reading the description, the seller goes on to say it's sometimes called Sea Opal, Tiffany Stone*, Opalized Glass, Opal Quartz, and other names.  This makes it seem as though Opalite is correctly called other names----when, in fact, those are just manufacturers' brand names that are given to Opalite EXPRESSLY to mislead the public.  There is no such gemstone as "Sea Opal" or "Opal Moonstone".  And Opalite is NOT quartz!

*There IS a stone called "Tiffany Stone", which is actually a stone mined in Utah seen in varying shades of

So-Called Tiffany Stone: NOT Opalite!

dark purple, lavender and creamy white with swirls of dark and light yellowish brown and pink areas takes a high polish as a cabochon.  It has NOTHING to do with Opalite!!  It was used by Tiffany in some jewelry at one time so it's been dubbed that name.  So to refer to Opalite as this gemstone---well, that's really beyond "creative".



But beyond that, they go on to describe it as a "glass resin" that is made with the actual mineral Dolomite plus metals!

I googled "Opalite+Dolomite" and can see that this particular description (Opalite made with Dolomite) is often used in the wiccan jewelry world, and therefore gives Opalite (which is ONLY glass) mystical healing properties.  Plus, a lot of people might think, "Oooh, Dolomite...so it IS a gemstone" since the name Dolomite sounds very technical and mysterious, until you know what Dolomite is!

In other words, it's a scam.

WHAT IS DOLOMITE?

Dolomite is a very common rock similar to limestone and is comprised of calcium magnesium carbonate.  These rocks were originally deposited as calcium carbonate muds that were post-depositionally altered by magnesium-rich pore water to form dolomite. It is the primary component of Dolomitic Marble and Dolomitic Limestone.  Dolomite has a Mohs hardness of 3.5.

Dolomite Marble 2" Piece

Dolomite Aggregate 1/2" pieces

Dolostone is used extensively in the construction industry. It is crushed and used to pave roads, as an aggregate in concrete and asphalt, and is used in making cement.  Dolomite is used in the production of bricks, glass and ceramics.  Because it is soft and is filled with "gaps" or "holes" within the rock, it is targeted by the oil and gas industry because these holes can be filled with natural gas or oil.

WHY WOULD DOLOMITE (Paving Gravel!)  BE USED TO MAKE OPALITE GLASS?

Simple answer:  it wouldn't, and it isn't.


If you'd like to read more about Opalite, please visit my post about it HERE.

Gem Love: SCAPOLITE

Yellow Scapolite

Scapolite is a gemstone that is very rare, and not well-known.  It comes in many colors, such as white, pink, grey, greenish, yellow, brown, and violet, and even blue.   The most common color is a bright honey-yellow. 

The name Scapolite comes from the Greek "skapos", meaning "shaft" due to its long, prismatic crystals.

Scapolite Crystal

Scapolite can easily be confused with Amethyst, Citrine, Chrysoberyl, and Golden Beryl.  But those gems are much harder than Scapolite.

Heat Treated Lavender Scapolite

Lavender Scapolite is heat treated, and unstable (the color will fade when exposed to sunlight).

Scapolite is a soft stone, similar to Opal.  It has a Mohs hardness of about 5.5 to 6.  It's most suitable to pendants and earrings.

Very small pockets of Scapolite can be found in the US and around the world.  Gemstone sources are found in Minas Gerias, Brazil; Madagascar, Tanzania, Canada, Switzerland and Burma.  It can also be found in Mt. Vesuvius, Italy and in Norway and Mexico.

Luster is vitreous on freshly exposed crystals or surfaces but weathering causes a dulling of the luster, due to the softness of the stone.  Scapolite will often fluoresce either orange, yellow or more rarely red under ultraviolet light---quartz and beryl minerals will not. Associated minerals include the garnet minerals almandine and andradite, actinolite, microcline, pyroxenes, apatite, andalusite, zircon, sphene, diopside and muscovite.

Cat's Eye Scapolite

Gemstone-quality scapolite usually exhibits excellent transparency. Some of the less transparent material will exhibit chatoyancy or the cat's eye effect when cut as cabochons. Cat's eye stones are rather rare and desirable as they tend to have exceptionally sharp eyes.

Wernerite, 'Pink Moonstone', Lavender Cat's Eye Scapolite, Violet Cat's Eye Scapolite, Pink Cat's Eye Scapolite, Mizzonite, Dipyre, Marialite and Meionite are lesser known gemstone trade names and mineral associations.

Rhodium Plated Sterling Silver: What Is Rhodium?

A lovely etsian sent me an email today and said they were confused, because I described a bracelet as Sterling Silver but also Rhodium plated.

Rhodium plated fine jewelry (like Sterling Silver) is SO common  that I never realized that there could be any confusion. It never occurred to me!  I know I've seen Rhodium plated (and gold plated) base metal chains and hydrangea leaf charms and things all over etsy (which are given a "flash" of Rhodium or gold), but I never really thought that people might not realize that fine PRECIOUS metals are also Rhodium plated. So I thought I'd explain it here.
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Rhodium is the most expensive metal on Earth.  It is used to plate high-end jewelry made of Sterling Silver, White Gold and even Platinum.  It provides a very high, and very lustrous finish and helps prevent oxidation (tarnish) on Sterling Silver.

Some lower-end jewelry such as brass is sometimes Rhodium plated to give it the look of high-end jewelry.  Rhodium plated brass will look just like white gold or Sterling Silver, but will not be hallmarked.  Sterling is always hallmarked "925" or "Sterling" by law, and gold is hallmarked by karat (10k, 14k, 18k, etc.).

What is Rhodium?

Rhodium

Rhodium is a chemical element that is a rare, silvery-white, hard, and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45.  It has a very high melting point at 3,565°F. 

It is one of the most expensive metals, at almost twice the price of platinum and three to four times the cost of gold. Rhodium has an extremely high reflectivity and doesn't normally form an oxide, even when heated.

Because rhodium is a "noble metal" and inert, it withstands corrosion and makes Sterling Silver and White Gold more durable as well.

Additionally, rhodium is hypoallergenic. White gold and even sterling silver employ nickel to provide the whiteness of white gold, however, approximately 20% of women will have some form of allergy to nickel. Thus, by rhodium plating, a possible allergen is removed from contacting your skin. 

Why Is Sterling Silver Often Rhodium Plated? 

Pure silver (99.99% silver) is very soft and scratches easily and is too soft to hold gemstones. Other metals, mostly copper, is alloyed with pure silver to form Sterling Silver.  Sterling is hallmarked .925 indicated that it is, by law, 92.5% pure silver, and 7.5% copper (or occasionally nickel). 

Rhodium plating can dramatically increase the long term durability, brightness and luster of the finish.  Rhodium plated sterling silver will remain tarnish-free for a longer period of time than unplated sterling silver.

Why Is White Gold and Platinum JewelryAlso Rhodium Plated?

White gold is an alloyed metal--mixing yellow gold with nickel or other metals to achieve a whiter look.  However, it still has a slightly yellow cast.  To achieve the brightest finish, particularly on engagement and wedding rings, all white gold is Rhodium plated.  This also enhances the diamonds or gemstones set in the white gold, and provides a hypoallergenic finish (since a large number of people are sensitive to nickel).  Platinum jewelry ils also Rhodium plated.  That seems strange, but platinum is rough-looking and more grey, a little bit like a new nickel, and plating it with Rhodium gives it that very shiny and bright, smooth look.

Does it Wear Off?

Yes, Rhodium will eventually wear off, especially on everyday rings like a wedding or engagement ring.  However, it's easily re-plated and jewelers recommend replating jewelry every 3 or 4 years.  The cost is about $45 to replate with Rhodium, and the original luster is returned.  Keep in mind that Rhodium plating will not eliminate dents and scratches but it will  make the jewelry more shiny and bright and more expensive looking.

Emeralds, Rubies and Sapphires from India are FAKE: Really DYED SILLIMANITE!

Ebay Seller with FAKE gemstones--from India

I've seen a LOT of gemstones from India lately that are very cloudy and opaque, but vivid colors of green, red and blue and are sold as emeralds, rubies and sapphires.  They are remarkably affordable and are very large.  The appear to be low-quality gemstones that have been enhanced.  I've wondered what these stones are, really, because there is no way that an emerald the size of a dime or quarter or larger would be set in silver and sold for WELL under $50, and often for $10 or less.  These kinds of gems from India are sold ALL over ebay and on etsy.  One ebay seller with "gems" from India even provides "Certificates" authenticating these stone as "genuine" mined Corundum rubies and sapphires, and Beryl emeralds, always described with "parting planes" that are visible with magnification.

"Emerald" Sillimanite

Today in my etsy feed I saw a very large green emerald two-stone pendant for $17.99!  The seller described it as "Emerald (Sillimanite)" from Jaipur, India.  It's a really beautiful pendant over 2" long, with fabulously green stones, elaborately set in solid sterling silver.

After a little internet searching, I've discovered that a number of articles have been written since 2009 regarding the use of the mineral Sillimanite in jewelry, that has been dyed and sold as emeralds, rubies and sapphires.  Testing was done on these stones to reveal this fraud.  Per gemologyproject.com:

A fibrous sillimanite dyed red simulating a ruby.

"Fibrous sillimanite is very often dyed to imitate various "precious" gemstones like ruby, emerald and others. This type of sillimanite has a massive fibrous like appearance under magnification and show color concentrations...Such dyed sillimanite is now very often encountered in India."

It would seem now that the vast MAJORITY of so-called "emeralds", "rubies" and "sapphires" from India are in fact dyed Sillimanite.  The big giveaway is that these stones are highly fibrous, and opaque, as you can see in the "ruby" above.

Dyed "Sapphire" Sillimanite

Interestingly, per The Gemology Project, in Sillimanite, Chatoyancy (cat's eye effect)  is common  in Sri Lankan blue-green stones and can have six-pointed stars which can imitate star sapphires, as seen in the photo, below right.

Chatoyant sillimanite cabochons

WHAT IS SILLIMANITE?

Blue Kyanite Crystal

It is a mineral also known as "fibrolite" and is named after Benjamin Silliman (1779-1864).  It is a member of the aluminosilicate series, which also includes Andalusite and Kyanite!

Sillimanite can naturally be found in the colors Sapphire blue, blue-green, colorless, white, gray, yellowish, brownish, greenish, bluish, violet-blue.  It can be transparent to highly fibrous.
Mohs hardness of 6 to 7.5.

60x Magnification showing Sillimanite Fibers

SO...a big thank you to the honesty of Etsy seller RavishingImpressions and to their GORGEOUS and affordable jewelry.  They were honest to include the "Sillimanite" disclosure right there in their title, and I really appreciate that.  It is a beautiful dyed stone that looks like a very opaque emerald, and is very affordable. 

If you encounter gems from India that look like the pictures here, and are described as precious emeralds, rubies or sapphires, and are very affordable, be very wary.  NEVER buy any "gemstones" from ebay, particularly from seller Gems-India who fraudulently state these stones are precious gemstones AND provide phony documentation.  The marketplace is FLOODED with misleading gemstones, and downright fraudulent misrepresentations, so as always, BUYER BEWARE!!

And now we all know!

Quartz Doublet: What Is It? Tinted GLUE???

"Green Quartz Doublets" or "Emerald Quartz Doublets"

I get Etsy's emails, and they feature stores or items (how they're chosen is anyone's guess!).  Today's "finds" had a lovely pair of earrings that looked like emeralds (NOT the exact ones pictured above--but very close).  So of course I clicked on it!

The earrings were $400 and described as "emerald like green quartz doublets" set in plated mystery metals.  That seems really steep for earrings, especially set in plated junk metals (not sterling silver) and even though their tags were "emeralds" and "emerald earrings" they were not described as emeralds at all. 

I've seen, and sold, Opal doublets and triplets.  Triplets are slices of actual opal that are sandwiched between onyx and a cap of clear quartz.  So opal triplets are true opals plus semi precious gemstones, making them affordable AND real.  A doublet is a "cap" of clear quartz adhered to a flat "slice" of opal---two pieces, without the third bottom stone, and therefore a doublet.  These are referred to as "assembled stones".  The important thing is to disclose that they are "triplets" and I described in my etsy listing exactly what an opal triplet is.  Honesty and full disclosure.

So, what are "green quartz doublets"?  Or any "quartz doublets"?  What two stones are used to make this a doublet?

Searching the internet, I see these "quartz doublets" are sold OFTEN on home shopping networks HSN.com, and ShopHQ.com (formerly ShopNBC) and other TV shopping channels.  So they're plentiful, but not much info available on those sites about the stone.

Blue Sapphire Quartz Doublet

But THE greatest website is RioGrandeJewelry.com.  Rio Grande is THE major supplier of metals (like sterling wire or pure gold grain) and gemstones and supplies to the jewelry industry.  And luckily, they are near me here in New Mexico and I use their expertise regarding vintage jewelry I have.  RioGrandeJewelry.com is selling a "Blue Sapphire Crystal Quartz Doublet" as pictured left for about $4 for a 6mm stone and $15 for a 12mm stone (HERE), with the description of the stone as follows (emphasis mine):

"This doublet is composed of a clear quartz top and bottom;  the adhesive that holds the two together provides the beautiful sapphire color."

The fact that "sapphire" in this stone is actually BLUE GLUE would account for the cheap price tag.  And any other "green quartz doublet" would also be worth next to nothing.  RioGrandeJewelry fully discloses what their stones are----it's the only place I trust.

If you look at that same RioGrande page and scroll down to their description of "Doublet Stones" which specifically describes the "green quartz doublets", you can read this:

What Is a Doublet Gemstone?

Producing consistent green and purple colors in laboratory-grown gemstones can be extraordinarily difficult. Doublets (sometimes called soudées*) allow labs to produce consistent colors by using a tinted adhesive to attach two clear pieces of laboratory-grown spinel. The crown and the pavilion are joined with the adhesive at the girdle.

Unless the stone is immersed in highly refractive liquid (such as water), it is impossible to tell that only the girdle zone of a doublet has color.

IMPORTANT: Because laboratory-grown spinel doublets are assembled with glue, it is important not to apply heat to the gemstone. To be safe, clean these gemstones using warm, soapy water and a soft brush.

*(Note: soudées is French for "welded".)  And Rio Grande then provides photos of a quartz doublet submerged in water, which allows you to see the thin layer of colored glue and the clear quartz becomes transparent--invisible!---in the water.
 
So unlike an Opal doublet or triplet where an actual SLICE of the gem is sandwiched between gemstones, and is considered an "assembled" stone,  a so-called "quartz doublet" is TINTED GLUE beween two pieces of quartz.  (Or tinted glue between two pieces of lab-created spinel.)

Emerald Quartz Doublet on ShopHQ

On ShopHQ.com as I mentioned already, they offer "emerald quartz doublets" set in jewelry.  They SORT OF disclose what this is as follows (and I'm sure their legal department says this is the BARE minimum information they can provide):

"Emerald quartz is created using natural, clear rock crystal or natural quartz and is assembled together with the colored layer in between the upper and lower portion of the stone. This method of assembly is permanent so the color will not fade. The doublet avoids any irradiation and thin surface treatments, like diffusion, that can chip away with time. Compared to common surface treatments, it also preserves the natural crispness of the quartz since the green hue comes from within the stone, thus allowing the gemstone to appear more brilliant and alive. Emerald quartz has a Mohs rating of 7. It can be safely worn on a daily basis and cleaned with regular jewelry cleaners. 

So they disclose that there is a "colored layer" but they DO NOT say it's glue.  That to me is misleading and disingenuous, trying to make buyers think the "colored layer" is emerald or a gemstone.  IT'S GLUE.

This explains why this is called a doublet, and not a triplet.  A triplet is made by sandwiching a slice of a stone (opal is common) between two layers of stones.  In a quartz doublet, there is NO third layer---just glue holding the two slices together.  If there were an actual slice of something between the layers, it would be called a triplet.

So-Called "Emerald Quartz" Doublet, Ebay

Looking on ebay (note: NEVER buy gemstones from ebay!), there are so-called "green quartz doublets" and "emerald quartz doublets" for sale for about $40 and less per pair.  Now you know that these aren't anything more than GREEN GLUE between two pieces of quartz!

It's interesting to know that the green (or purple, or other color) adhesive causes the entire gemstone to emanate with that color.  It's only when the stone is submerged in water that you can see the colored glue layer.  So you ARE getting a quartz gem (or spinel!) and the color can't scratch off, so that's a plus.

So the "green quartz doublet" earrings that Etsy is promoting are made from GREEN GLUE sandwiched between slices of quartz. Although they are quartz gemstones (as opposed to hydroquartz, or glass) their value is nowhere NEAR the price asked, and actually because these stones are set in plated base metal of some sort,  their intrinsic value is very very low.

I didn't know about the tinted glue until I researched "quartz doublets" myself (I don't sell them).  Is it possible the etsy earrings seller didn't realize what these doublets are?  It's  possible that the etsy seller didn't realize----ignorance isn't an excuse though, and sellers should always be informed as to what they are selling.   And buyers should research stones as well, and make informed buying choices.   And now we all know!

BUYER BEWARE!!!!!