A gemstone, or gem, is a type of material that is capable of being cut and polished for use in jewelry or other ornamental applications. Gems are most commonly made of minerals. Minerals are naturally occurring, inorganic, crystalline solids, of definite chemical composition. Examples are quartz and sapphire. However, certain rocks (such as lapis lazuli and opal) and occasionally organic materials that are not minerals (such as amber and pearl) are also used for jewelry and are therefore often considered to be gemstones as well. Diamonds, rubies, sapphires, and emeralds are classified as precious stones, and others, such as pearl, black onyx, opal, blue topaz, and moonstone, are called semi-precious stones. Interestingly, no difference exists between the two, rather this is a marketing classification invented years ago to give a false sense of value to the former.
Lapidary Arts and the Islamic Tradition
Humankind has always been drawn to the beauty gemstones radiate. They were known and used in the Indus Valley, and by the Ancient Egyptians, Mesopotamians, Greeks, and Romans—especially by the elites. The use of ornamental stones for jewelry through engraving, cutting, and polishing stones and gems, also called lapidary arts, is older than the use of metal.
Plenty of precious and semiprecious stones were already in use in regions that would later on become part of Islamic empires, such as India. Stones were strung into necklaces or bracelets, and used as turban festoons or sealstones. Following the Prophetic sunnah, they were often used in rings. The same stones were repeatedly recut and reused throughout centuries. Some of these can be found in the Imperial Treasury in Istanbul’s Topkapı Palace and the National Treasure in the National Museum of Iran. Examples of stones that were already distinguished early on are agate, diamond, ruby, topaz, sapphire, pearl, coral, jasper, hematite, rock crystal, and emerald.
Harun al-Rashid, the fifth Abbasid Caliph who ruled during the late 8th century CE, had a weak spot for precious stones and was a notable connoisseur. He is said to have sent the jeweler al-Sabbah, who happens to be the grandfather of the great scientist al-Kindi, to Ceylon to buy precious stones for him.
Mineralogy and Gemology and the Islamic Tradition
Writings on gemstones were translated into Arabic from the 6th to the 8th century CE. During the fourth and fifth centuries after the Hijra (10th-11th century CE), research on gems by Muslim scholars truly flourished. A significant part of what was written by Muslim scientists has been lost, although some works have survived in the form of monographs and entries in encyclopedic works. Examples of scholars exploring this field are Yuhanna ibn Masawaih (died 857 CE), Abu Yusuf Yaʻqub ibn Ishaq al-Sabbah al-Kindi (died 873 CE), Abu Muhammad al-Hasan al-Hamdani (died 945 CE), and Ikhwan al-Safa (9th-10th century CE).
These scholars used almost the same physical properties to identify and differentiate gemstones that are known to us today, such as colour, lustre, hardness, and crystal habit. Taking the lead in this regard was Abu Rayhan Muhammad ibn Ahmad al-Biruni (died 1048 CE), who wrote his major contribution, Treatises on How To Recognise Gems (الجماهر في معرفة الجواهر), between 1041 and 1049 CE.
al-Biruni uses color dimensions as a way to identify minerals and gemstones, giving a detailed description of the color of many of them. From slight color differences and different degrees of purity between minerals originating from different mines, he distinguishes how this might affect their financial value. He describes the following principal precious stones (الجواهر) and minerals: ياقوت (hyacinth, sapphire), ياقوت أحمر (ruby), ياقوت أخضر (green corundum), ياقوت جَمرْي (carbuncle), لَعْل (spinel), بيجادي (garnet), ألماس (diamond), سنباذج (emery), لؤلؤ (pearl), زُمُرُد (emerald), فيروزَج (turquoise), عقيق (agate), جَزْع (onyx), بَلّور (rock crystal), جَمَشْت (amethyst), لازوَرد (lapis lazuli), دَهَنْج (malachite), يَشْم (jade), يَشْب (jasper), سَبَج (obsidian), بادْزَهْر (bezoar), كَهْرُبا (amber), مغناطيس (magnetite), الشَادَنَج (hematite), زجاج (glass), مينا (enamel), and قيسَع صيني (porcelain).
Gems and Medicine
Drugs of mineral origin, especially gems, are known to be extensively used in the Unani Medicine tradition, both as single drugs and as compound formulations. Ibn Sina (981-1037 CE) has made a leading contribution to the fields of geology and mineralogy in his famous encyclopaedia of philosophy and natural sciences, The Book of Healing (كتاب الشفاء). In Part 2, Section 5, one finds the Article on Mineralogy and Meteorology, in which he describes healing properties of minerals and plants.