The birthstone for July is the Ruby. Rubies are one of the hardest natural gems. Only moissanite and diamond are harder. Rubies (from the Latin “ruber” for red) are the red version of the mineral corundum (aluminum oxide) which is colorless in its pure state (rubyis an allochromatic gem - see below). In rubies, some chromium (about one percent) replaces the aluminum and the chromium atoms reflect light in the red part of the visible light spectrum. This reflected red light is what your eyes see and is what gives rubies their red coloring.
Other factors like defects can affect the color we see and whether you view the stone in daylight or fluorescent light. Rubies are considered the king of gems and represent love, health and wisdom. Rubies are the most valuable gemstones. The value of a gem increases based on its color and quality. Rubies are the most valuable gemstones.
Rubies vary in color from deep red to light pink and they can be found in many places. The best quality rubies are from Myanmar (Burma), but they can also be founds in many places, including the United States. In the United States, a few rubies have been found in Montana, North and South Carolina, and Wyoming.
Gems that receive their color from impurities are known as allochromatic. These gems contain impurities of light absorbing elements. The colors we see are due to the presence of these trace elements. Other gems, such are malchite or turquoise, contain color causing elements that are part of their chemical structure. These are known as idiochromatic gems and these stones are never found colorless.
Earlier blog posts on birthstones