Ruby in Zoisite in nice rough small chunks.

The ruby ​​(derived from the Latin ruber, "red") is a red gemstone, a variety of the mineral corundum in which the color is mainly caused by chromium. Natural rubies are exceptionally rare, while man-made ones are relatively inexpensive. In addition to the clear gemstone ruby, there is also the less clear semi-precious stone of the same name. This stone has been valued since ancient times. The oldest written records of ruby ​​mining mention quarries in Burma. From there the stones came through trade routes to the courts and temples of the ancient Egyptians and Greeks. In the Middle Ages, rubies were also popular in Rome. Initially they were machined into an oval shape. The very large and beautiful stones also have their own names. The ruby ​​was considered the stone of life, strengthening the heart and returning strength. In antiquity and the Middle Ages, magical powers were attributed to rubies. The value of the ruby ​​is also recognized in the Bible, although in some of those passages the point is precisely that there are treasures of greater value: wisdom is more precious than rubies (Proverbs 3:15) and the worth of a good wife far exceeds that of rubies in the eyes of her husband (Proverbs 31). Also in Job 28 ruby ​​is mentioned as one of the treasures that man seeks in places where the priceless and untraceable wisdom of the living God is not to be found. It should be noted, however, that what is sometimes identified in the King James Version as 'ruby', appears under completely different names in some other translations. In this interpretation, one should take into account what was regarded as valuable in the culture and time of the preparation of the translation in question. Ruby also has mythological significance. The ruby ​​is one of the "nine gems" in the Thai Order of Nine Gems. Rubies are mined in Africa, Asia and Australia. They are most commonly found in Burma, Sri Lanka, and Thailand, although they have also been found in Montana and South Carolina. Rubies have a hardness of 9 on the Mohs hardness scale, being surpassed in hardness only by diamonds among natural gemstones. Other varieties of corundum are called sapphire. Ruby gemstones are valued according to several characteristics such as size, color, clarity and cut. All natural rubies have imperfections and only artificial rubies can be completely free of imperfections. The fewer the number and less obvious the imperfections, the more valuable the ruby ​​is, unless there are no imperfections at all (i.e. a "perfect" ruby). In that case, it could be an artificial ruby. Some artificial rubies have substances added to them so that they can be identified as artificial, but most require the intervention of a specialist appraiser to determine the precise value.