BIRTHSTONE FOR JULY!
There’s no better way to demonstrate your love than by giving a ruby in celebration of a July birthday. Rubies arouse the senses, stir the imagination. Ruby is a variety of the gems species corundum. It is harder than any natural gemstone except diamond, which means a ruby is durable enough for everyday wear. Fine-quality ruby is extremely rare, and the color of the gem is most important to its value. The most prized color is a medium or medium dark vivid red or slightly purplish red. If the gem is too light or has too much purple or orange, it will be called a fancy-color sapphire.
CHEMISTRY: Al2O3
CRYSTALLOGRAPHY: Hexagonal
REFRACTIVE INDEX: 1.757 – 1.779
HARDNESS: 9
SPECIFIC GRAVITY: 3.99 – 4.0
CLEAVAGE: None
HEAT SENSITIVE: No
WEARABILITY*: Excellent
SPECIAL CARE INSTRUCTIONS: None
Ruby is red corundum, all other color varieties of corundum being referred to as sapphire. The name “Ruby” is from Latin – ruber - and is based on the gem’s red color. That fact notwithstanding, the ruby color range includes pinkish, purplish, orangey, and brownish red depending on the chromium and iron content of the stone. The trace mineral content tends to vary with the geologic formation which produced the ruby, so original place designations such as Burmese and Thai have come in later years to be sometimes used in describing color.
Most authorities expect a medium to medium dark color tone in a ruby, naming stones lighter than this, pink sapphire — but there is no general agreement exactly where the line is to be drawn.
The old joke about questionable stones goes: Whether it’s a ruby or a pink sapphire depends on whether you’re the buyer or the seller.
Ruby rough of lower quality is used in great quantities to make beads, carvings, and other ornamental objects. The silk, which is so common in corundum, can, if sufficiently abundant, and precisely arranged, lead to asterism. With proper cutting, this creates star rubies. Today there are heating and diffusion processes that can increase the rutile content and improve such gems. Synthetic star corundums were very popular in the 1950′s under the trade name “Linde Stars” and are still under production.How valuable is a Ruby?
Rubies are the most valuable members of the corundum family. Large gem quality rubies can be more valuable than comparably sized diamonds and are certainly rarer. There is a relative abundance of smaller, (1-3 carat,) blue sapphires compared to the scarcity of even small gem quality rubies, making even these smaller stones relatively high in value.
