Tuesday, April 23, 2013

Cool Blues

After a slushy, overcast winter, I always long for the blues … the azure sky of a clear summer day, the rich cobalt of a warm nightfall, and the ever-changing hues of ocean water.

Whichever shade of blue you respond to, there’s a blue gemstone that captures it. Here are a few to consider.

Hardness: 8.0 out of 10.0 on the Mohr Scale

Aquamarine — the March birthstone— is a naturally blue member of the beryl family that ranges in color from a pale, cool blue to a warmer, more saturated blue-green. (The blue-green color is considered the most desirable.) Most of today’s aquamarines are mined in Brazil. 

A rough aquamarine crystal

Whether clear or opaque, aquamarines make gorgeous jewelry. If you’re on a budget, choose the opaque variety, which may be carved, cut en cabochon, or fashioned into beads that seem to glow from within. Because they have fewer inclusions, the clear stones command a higher price. But the real show-stoppers are the extremely rare cat’s eye and star aquamarines. A Google Image search pulls up some amazing photos of both.  

Blue Topaz
Hardness: 8.0 out of 10.0 on the Mohr Scale

Straight from the ground, most gem topaz is a reddish-yellow color. But someone discovered that adding radiation and heat to pale topaz stones, turns them an enchanting blue. “London blue”, the deepest and most expensive shade, may have greenish or grayish undertones. “Swiss blue” is a medium green-blue, like the most coveted aquamarine. And “sky blue” is the lightest color of all. 

London blue topaz

If you want the look of aquamarine without the price tag, blue topaz is a great alternative. But if you’re going for a ring, make sure the setting protects the stone. Topaz is hard, but it can be prone to chipping.

Hardness: 7.0 – 7.5 out o 10.0 on the Mohr Scale

Iolite (or “”water sapphire”) is a richly colored, blue-violet gem that’s a bit of a chameleon. Stones with a stronger blue cast can look like blue sapphires, while the lighter, more violet-hued stones can look like high-end tanzanite.

But unlike those two gems, iolite has a curious natural property. Its crystals appear blue, yellow, or even clear when viewed from different angles.
An iolite crystal. Note the gold-colored facet on the left. 
This property, called “pleochroism”, creates a striking visual effect. But iolite gems must be skillfully cut so their rich blue color shows from the top. When you purchase one, be selective; you don’t want to have to tilt the stone to see that lovely color!  

Blue Sapphire
Hardness: 9.0 out of 10.0 on the Mohr Scale

Sapphire is the world’s second-hardest natural mineral, and while it comes in many colors, blue is by far the most popular. Blue sapphires range from a light grey-blue or sky blue to the extremely rare, intense, velvety blue of stones from Kashmir and Burma. 

12    Date: 27 July 2005

A spectacular Kashmir sapphire

Most of today’s sapphires come from Sri Lankan and Madagascar. But you can also find them much closer to home ... in Montana!

Eye-clean blue sapphires are always desirable. But in the hands of a good gem cutter, so are stones that have the fine, needle-like inclusions known as “silk”. When these inclusions meet from several different directions, a star sapphire is born. The best star sapphires are transparent or translucent, with deep color and a sharply defined and well-centered star.

There are many more gemstones in this color family ... but I'm out of time.

You can take it from here.

Ain't the blues a fabulous thing?