The ruby, as with most gemstones, gain value depending on their size, color, and clarity, much of which is determined by the skill of the stone cutter. Rubies in the National Museum of Natural History, Washington DC Durability and Care The Ruby is a good durable stone for everyday wear, and will not scratch or crack as easily as some other colored gemstones, it rates a 9 on the Moh's scale, with diamond being the hardest at 10. Be aware though that many common household cleaners and also lemon juice can damage rubies, so always remove your jewelry before using any of these. Real or Synthetic? There are both real rubies and synthetic rubies available in the marketplace. Real rubies are more rare and usually therefore more expensive. They also have inclusions or imperfections within the stone. Stones can be 'filled' generally with glass or plastic, this helps to cover undesirable imperfections and/or inclusions and improve the outward appearance of the finished stone, (this is also true for emeralds). Rubies are often also heat treated to enhance both their appearance and saleability. If a seller knows that a gemstone has been treated they should disclose the treatment to the prospective purchaser. The picture on the left shows a natural ruby wuth inclusions Synthetic rubies have been produced from as early as the mid 1800's. Many of the rubies found in lower end jewelry are synthetic. However since their physical, optical and chemical makeup are essentially the same as a natural ruby - they are no less appealing to the eye, just more affordable. But of course, ultimately, it is down to personal preference. What are Star Rubies? This is a phenomenon called 'asterism' and occurs in stones that are cut as en cabochon - a smooth rounded stone, rather than faceted. It looks like a star in the stone. In a good quality stone, the star should be unbroken and centered. If you are in a jewelry store, ask to have a look at the stone through a jewelers loupe, you may be able to see inclusions such as rutile needles, more commonly referred to as silk. These are not always a bad thing however, since they create the star ruby, or cats eye, both of which are caused by the formation of silk. Did you know that the Rajaratna Ruby, the largest ruby in the world, is actually a Star Ruby? The picture on the right is an example of a Star Ruby. Rubies are mined in various places but probably the best known are from Thailand or Burma. In medieval Europe rubies were worn and believed to be a guarantee for health, wealth, wisdom and success in love.  In Burma, rubies were worn by warriers since it was a belief that the ruby would make them invincible when in battle. Ruby and Sterling Silver Tear Drop Earrings, Available from GemstonesandCrystals on Etsy The following extract is taken from an article by Bijan Aziz who is the owner and Web Master for The Jewelry Hut. http://www.thejewelryhut.com The best source for fine Diamond, gemstone, and Pearl Jewelry on the Web" "Thai rubies can vary tremendously in hue and tone, going from a light to a dark red varying degrees of a bluish undertone, giving them a purplish cast and making them look like the much cheaper reddish purple gemstone, the garnet. While some Thai rubies can have very fine color rivaling the Burmese (these are very expensive), most Thai stones are much less expensive than the Burmese, primarily because the color can’t compare. African rubies from Tanzania usually have a tint or undertone of brown or orange, which makes them also much cheaper than the Burmese reds, but depending upon the precise shade, often more valuable than the Thai ruby, depending on the lather’s color. Rubies from newly discovered deposits in Kenya, Cambodia, Vietnam, and parts of China are very close in hue and tone to Burmese, and may also retain their color in all light. These stones can command very high prices if other quality factors are fine. Ceylon, rubies are also encountered with relative frequency. However, these are usually so pale that in the United States they would called “pink sapphire” rather than ruby since the tone is consistently so light. The saturation of color is too weak to be technically described as ruby, since ruby should be red, not pink. You should be aware that in the United States, the color must be deep enough to be considered red to be called “ruby” while in other parts of the world, the name “ruby” may be applied if the stone falls anywhere in the pink to red range.  It should be noted that sapphire and ruby are the same stone, physically and chemically. The red variety is called ruby, while the equally popular blue is called sapphire. Both belong to the “corundum” family." End of quote. Photographs used for this article available under the Creative Commons Deed http://creativecommons.org/licenses/by-sa/3.0/ Tweet

Specific Gravity 4.00

Refractive Values 1.76 - 1.77

birefringence (doubly refractive gems only) 0.008

Lustre Vitreous