Rubies have been revered since ancient times. The Bible and ancient Sanskrit writings regarded ruby as the most precious of all gemstones. In ancient Sanskrit, ruby is called ratnaraj, or “king of precious stones.” In the Bible, only wisdom and virtuous women are “more precious than rubies.” Even diamonds were considered common in comparison to the fiery gemstone. Named from the Latin word for its hue, ruber, ruby is the epitome of the boldest of colors and symbolic of passion, protection, and prosperity.
Ruby is the red variety of the corundum mineral species. All other colors of corundum are called sapphire; thus, color is vital for this prized stone. Ruby is one of the most durable minerals, a crystalline form of aluminum oxide, and it has a hardness of 9 on the Mohs scale. Diamond is the only natural gemstone harder than ruby.
Colored by chromium, the element gives ruby its red color, as well as its glowing fluorescence. Few rubies grow large enough to crystallize into fine gem material due to the coloring agent, chromium, since it also increases the chances of cracks and fissures.
Rubies are available in a range of red hues, from orangey red to violet red. Ruby is found throughout Southeast Asia and Africa, with Mozambique, Madagascar and Burma, now known as Myanmar. Certain color tones are associated with different mines: the Mogok mine from Myanmar produces a deep blood-red color with purplish hues and are the most sought-after locale. Color alone cannot tell you the origin of a stone, a laboratory report may be required. When confirmed, stones from Myanmar command a premium, especially if the color is natural.
Generally, the majority of the world’s rubies are subjected to heat treatment to improve their color. High temperatures maximize the purity and intensity of their red hue. Impurities may dissolve or become less noticeable after heating; however, heating will only improve the color if the gemstone contains the proper chemistry. If ruby shows no signs of heating, it is very rare and is a true treasure. The stone’s natural color must be confirmed by a laboratory report if it is to command a premium.
Rubies are readily available in sizes up to two carats, but larger sizes can be obtained.
Ruby is most common in oval and cushion shapes. Other shapes may be difficult to find in sizes above a carat. Fine rubies above five carats are extremely rare and valuable.
The passionate red color of rubies make the stone an ideal choice for a romantic gift. Ruby is the birthstone for July and the gem for the 15th and 40th anniversaries.