Ruby is a variety of corundum, like sapphire. It owes its name to its red color (Latin "rubeus").

It was not attached to the group of corundum until 1800.  Before that date, it was associated with "carbuncles" with pyrope garnet and red spinel. The red color is not identical for all rubies from the same deposit.

The most sought-after of all the colors is called "pigeon's blood", a strong red with a hint of blue. The color is attributed to the presence of chromium. Rubies and sapphires are the hardest minerals after diamonds. Inclusions are very common. They do not determine the quality of the gem; they guarantee its authenticity as a natural ruby compared to synthetic rubies.

The nature of the inclusions provides many indications of its type of deposit. The most important operations are in Burma, Thailand (Siam), Ceylon and Tanzania. Other deposits exist in Afghanistan, Mozambique or Madagascar... Ruby is one of the most expensive gemstones. Large ruby gems are rarer than diamonds of the same size. The ruby is a great classic of jewelry: rings, earrings, necklaces, but it is also found on the crowns of the most prestigious collections.