Gemstone

Group of precious and semiprecious stones—both uncut and faceted—including (clockwise from top left) diamond, uncut synthetic sapphire, ruby, uncut emerald, and amethyst crystal cluster.

A gemstone (also called a gem, fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments.[1][2] However, certain rocks (such as lapis lazuli and opal) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) are also used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone.

Apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter; a diamond cutter is called a diamantaire.

Characteristics and classification

A selection of gemstone pebbles made by tumbling rough rock with abrasive grit, in a rotating drum. The biggest pebble here is 40 mm (1.6 in) long.

The traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between precious and semi-precious; similar distinctions are made in other cultures. In modern use the precious stones are diamond, ruby, sapphire and emerald, with all other gemstones being semi-precious.[3] This distinction reflects the rarity of the respective stones in ancient times, as well as their quality: all are translucent with fine color in their purest forms, except for the colorless diamond, and very hard, with hardnesses of 8 to 10 on the Mohs scale. Other stones are classified by their color, translucency and hardness. The traditional distinction does not necessarily reflect modern values, for example, while garnets are relatively inexpensive, a green garnet called tsavorite can be far more valuable than a mid-quality emerald.[4] Another unscientific term for semi-precious gemstones used in art history and archaeology is hardstone. Use of the terms 'precious' and 'semi-precious' in a commercial context is, arguably, misleading in that it deceptively implies certain stones are intrinsically more valuable than others, which is not necessarily the case.

In modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition. For example, diamonds are made of carbon (C) and rubies of aluminium oxide (Al
2
O
3
). Next, many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used is habit, the form the gem is usually found in. For example, diamonds, which have a cubic crystal system, are often found as octahedrons.

Gemstones are classified into different groups, species, and varieties.[5] For example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow) and morganite (pink), which are all varieties of the mineral species beryl.

Gems are characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture and luster. They may exhibit pleochroism or double refraction. They may have luminescence and a distinctive absorption spectrum.

Material or flaws within a stone may be present as inclusions.

Gemstones may also be classified in terms of their "water". This is a recognized grading of the gem's luster, transparency, or "brilliance".[6] Very transparent gems are considered "first water", while "second" or "third water" gems are those of a lesser transparency.[7]

Other Languages
Afrikaans: Edelsteen
Alemannisch: Edelsteine
العربية: حجر كريم
asturianu: Xema (xeoloxía)
azərbaycanca: Qiymətli daşlar
বাংলা: রত্নপাথর
башҡортса: Аҫыл таштар
беларуская: Каштоўныя камяні
беларуская (тарашкевіца)‎: Каштоўныя камяні
català: Gemma
čeština: Drahokam
Cymraeg: Glain
dansk: Smykkesten
Deutsch: Schmuckstein
español: Gema
Esperanto: Gemo
euskara: Harribitxi
فارسی: گوهرسنگ
français: Gemme
客家語/Hak-kâ-ngî: Pó-sa̍k
한국어: 보석
Hawaiʻi: Gema
हिन्दी: रत्न
hrvatski: Drago kamenje
Ido: Gemo
Bahasa Indonesia: Batu permata
עברית: אבן חן
Basa Jawa: Watu permata
қазақша: Асыл тастар
Kiswahili: Kito (madini)
Kreyòl ayisyen: Pyè presye
Кыргызча: Асыл таштар
latviešu: Dārgakmens
Lëtzebuergesch: Eedelsteen
lietuvių: Brangakmenis
Limburgs: Aedelstein
magyar: Drágakő
македонски: Скапоцен камен
Mìng-dĕ̤ng-ngṳ̄: Bō̤-siŏh
မြန်မာဘာသာ: ကျောက်မျက် ရတနာ
Nederlands: Edelsteen
नेपाल भाषा: थी
日本語: 宝石
norsk: Edelsten
norsk nynorsk: Smykkestein
occitan: Gema
oʻzbekcha/ўзбекча: Javohirlar
ਪੰਜਾਬੀ: ਨਗ
português: Gema (mineralogia)
Runa Simi: Umiña
Scots: Gemstane
සිංහල: මැණික්
Simple English: Jewel
slovenčina: Drahokam
slovenščina: Dragulj
српски / srpski: Драго камење
srpskohrvatski / српскохрватски: Dragulj
suomi: Jalokivi
svenska: Ädelsten
Tagalog: Batong-hiyas
Türkçe: Değerli taş
اردو: جواہرات
Tiếng Việt: Ngọc
文言: 寶實
ייִדיש: איידלשטיין
粵語: 寶石
中文: 寶石