Sunday, December 15, 2013

Gemstone Love: LAPIS LAZULI

Polished Lapis Lazuli Block
King Tut's Mask
Lapis Lazuli, also known as just "Lapis", is a semi precious stone that has been prized for its beautiful deep blue color since antiquity.  It has beautiful flecks of gold pyrite within the blue stone.  It is a stone, not a mineral and not a crystal.  It has been mined in Afghanistan since 7,000 b.c. and was used as the eyebrows in King Tut's mask.  In ancient times, Lapis along with Turquoise were considered the most valuable stones.

At the end of the Middle Ages, Lapis was exported to Europe where it was ground and used as "ultramarine" -- the finest and most expensive blue pigment.  It was used by the most important artists of the Baroque and Renaissance periods. Vermeer's Girl With a Pearl Earring uses Ultramarine for her head scarf.
Vermeer's Girl with a Pearl Earring

Today, most Lapis is still mined in Afghanistan, but is also found in Chile, Canada, the United States and Russia.

The name "Lapis" comes from the Latin word for stone, and from the Arabic word for blue, "Azul".   It literally means "blue rock" and it is a rock, not a mineral.  It is composed of a variable mixture of the minerals lazurite, pyrite and calcite. The finest Lapis Lazuli is uniformly deep blue in color, opaque to semi-translucent and consists almost totally of lazurite.

I see pendants made of Lapis that have been carved into "points" or even "double terminated" points, like naturally occurring crystals, on etsy and elsewhere.  This is weird because Lapis is NOT a crystal at all, and is merely made of stone (rock!) and is carved in this shape for some reason.  Very odd.

Thursday, December 5, 2013

Something Beautiful: ROSE GOLD

3 Colors of Gold
Rose Gold is sometimes called Pink Gold, or even Red Gold.  It has all the value and properties of yellow gold, but because it has a higher content of copper, Rose Gold has a beautiful, soft pink color that goes well with most skin tones.  In fact, there are ranges of color within Rose Gold.   I LOVE Rose Gold because it's a little more unique than the typical yellow or white gold, and it seems to tone down the bright "flash" of stones, giving it a more elegant or vintage look.  As it was popular in Russia at the beginning of the nineteenth century, it is also known as Russian gold, but this term is now basically obsolete.

But What Makes It Pink?

Pure 24k gold is yellow, and is very soft.  It is alloyed with other elements to produce colors and other karats.  The most common karat grades of gold, in addition to pure 24K (100% gold), are 22K (92% gold), 18K (75% gold), 14K (58% gold), 10k (41% gold) and 9K (38% gold).  For example, alloys which are mixed 14 parts gold to 10 parts alloy create 14K gold, 18 parts gold to 6 parts alloy creates 18k, etc.

There are hundreds of possible alloys and mixtures, but in general alloying gold with silver will color gold white, and the addition of copper will color it red (or pink). A mix of around 50/50 copper and silver gives the range of yellow gold alloys the public is accustomed to seeing in the marketplace. A small amount (0.2%) of zinc is sometimes added to give the gold added strength and hardness.

There are three general classifications of colored golds:
  • the Au-Ag-Cu system, producing white, yellow, green and red golds;
  • the "intermetallic" compounds, producing blue and purple golds, as well as other colors. These are typically brittle.
  • the surface oxide layers, such as black gold; the colored surface is prone to wear off.

Although the names are often used interchangeably, the difference between red, rose, and pink gold is the copper content – the higher the copper content, the stronger the red coloration. A common alloy for rose gold is 75% gold and 25% copper by mass (18k). But it's also common for 18 karat rose gold to typically add about 4% silver to 75% gold and 21% copper to give a rose color. Since rose gold is an alloy, there is no such thing as "pure rose gold".   The highest karat version of rose gold is also known as "crown gold", which is 22 karat.  14 karat red gold is often found in the Middle East  and contains 41.67% copper.

During ancient times, due to impurities in the smelting process, gold frequently turned a reddish color. This is why many Greco-Roman texts, and even many texts from the Middle Ages, describe gold as "red"!

<------Check it out!  Gold & Co. in the UK has created the world's first 24k GOLD and ROSE GOLD iPhone5 (two separate models). Expensive, and only available in Dubai.  AND, they're not solid gold---just gold plated.  I have no idea the price.