A gemstone is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks and occasionally organic materials that are not minerals 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 and notoriety are other characteristics that lend value to gemstones.
Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide (α-Al2O3) with trace amounts of elements such as iron, titanium, cobalt, lead, chromium, vanadium, magnesium, boron, and silicon. The name sapphire is derived via the Latin "sapphirus" from the Greek "sappheiros", which referred to lapis lazuli. It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors. Red corundum stones also occur, but are called rubies rather than sapphires. Pink-colored corundum may be classified either as ruby or sapphire depending on locale. Commonly, natural sapphires are cut and polished into gemstones and worn in jewelry. They also may be created synthetically in laboratories for industrial or decorative purposes in large crystal boules. Because of the remarkable hardness of sapphires – 9 on the Mohs scale (the third hardest mineral, after diamond at 10 and moissanite at 9.5) – sapphires are also used in some non-ornamental applications, such as infrared optical components, high-durability windows, wristwatch crystals and movement bearings, and very thin electronic wafers, which are used as the insulating substrates of special-purpose solid-state electronics such as integrated circuits and GaN-based blue LEDs. Sapphire is the birthstone for September and the gem of the 45th anniversary. A sapphire jubilee occurs after 65 years.
The Hope Diamond is a 45.52-carat (9.104 g) diamond extracted in the 17th century from the Kollur Mine in Guntur, India. It is blue in color due to trace amounts of boron. Its exceptional size has revealed new information about the formation of diamonds.
Demantoid is the green gemstone variety of the mineral andradite, a member of the garnet group of Minerals. Andradite is a calcium- and iron-rich garnet. The chemical formula is Ca3Fe2(SiO4)3 with chromium substitution as the cause of the demantoid green color. Ferric iron is the cause of the yellow in the stone.
The Gemological Institute of America (GIA) is a nonprofit institute based in Carlsbad, California. It is dedicated to research and education in the field of gemology and the jewelry arts. Founded in 1931, GIA's mission is to protect buyers and sellers of gemstones by setting and maintaining the standards used to evaluate gemstone quality. The institute does so through research, gem identification and diamond grading services and a variety of educational programs. Through its library and subject experts, GIA acts as a resource of gem and jewelry information for the trade, the public and media outlets.
The Moussaieff Red Diamond is a diamond measuring 5.11 carats with a triangular brilliant cut, rated in color as Fancy Red by the Gemological Institute of America. It is the world's largest known red diamond, the rarest of all diamond colors.
The Great Chrysanthemum Diamond is a famous diamond measuring 104.15 carats with a pear-shaped modified brilliant cut, rated in colour as Fancy Orange-Brown and I1 clarity by the Gemological Institute of America. The Great Chrysanthemum is roughly the same size as the re-cut Kohinoor and almost three times the size of the Hope Diamond, The Great Chrysanthemum has the dimensions of 39.10 x 24.98 x 16.00 mm. and features 67 facets on the crown, 57 facets on the pavilion and 65 vertical facets along the girdle. The diamond, designed as a pendant, became the central focus of a necklace with 410 oval, pear-shaped, round and marquis diamonds.
Harry Winston was an American jeweler. He donated the Hope Diamond to the Smithsonian Institution in 1958 after owning it for a decade. He also traded the Portuguese Diamond to the Smithsonian in 1963 in exchange for 3,800 carats of small diamonds.
George Shirley Switzer was an American mineralogist who is credited with starting the Smithsonian Institution's famed National Gem and Mineral Collection by acquiring the Hope Diamond for the museum in 1958. Switzer made the arrangements when renowned New York City jeweler Harry Winston decided to donate the Hope Diamond to the Smithsonian.
International Gemological Institute (IGI) is a diamond, colored stone and jewelry certification organization. IGI is headquartered in Antwerp, Belgium, and has offices in New York City, Hong Kong, Mumbai, Bangkok, Tokyo, Dubai, Tel Aviv, Toronto, Los Angeles, Kolkata, New Delhi, Surat, Chennai, Thrissur, Ahmedabad, Shanghai, and Cavalese. Established in 1975, IGI is the largest independent gemological laboratory worldwide. It also runs Schools of Gemology in several locations around the globe.
The Maharaja of Indore Necklace is a diamond and emerald-studded necklace. As of 2008, it is on display at the National Museum of Natural History in Washington, D.C., United States. It was originally named the Spanish Inquisition Necklace by the American jeweller Harry Winston, though it had no known connection with the historical Spanish Inquisition. The name was changed in 2021 by the Smithsonian Institution to reflect its actual provenance, having been first owned by Tukoji Rao III, Maharaja of Indore in the early 20th century.
The Napoleon Diamond Necklace is a diamond necklace commissioned by Napoleon I of France c. 1811–1812 from the Parisian jeweler Marie-Étienne Nitot. It is currently on display in the Smithsonian National Museum of Natural History in Washington, D.C..
The Nassak Diamond is a large, 43.38 carats (8.676 g) Golconda Diamond that originated as a larger 89 carat diamond in the 15th century in India. Found in Golconda mines of Kollur and originally cut in India, the diamond was the adornment in the Trimbakeshwar Shiva Temple, near Nashik, in the state of Maharashtra, India from at least 1500 to 1817. The British East India Company captured the diamond through the Third Anglo-Maratha War and sold it to British jewellers Rundell and Bridge in 1818. Rundell and Bridge recut the diamond in 1818, after which it made its way into the handle of the 1st Marquess of Westminster's dress sword.
Richard T. Liddicoat, Jr. was an American gemologist. Liddicoat was an educator in gemology, who also made contributions in the area of diamond quality grading and gem identification. Liddicoat was the Chairman of the Board of Governors at the Gemological Institute of America (GIA).
The Jonker diamond was found at the Elandsfontein mine in South Africa by Johannes Jacobus Jonker on 17 January 1934. The diamond was 726 carats, which at the time was the fourth largest uncut gem ever found.
Golconda diamonds are mined in the Godavari delta region of the present-day states Andhra Pradesh and Telangana, India. Golconda Fort in the western part of modern-day Hyderabad, was a seat of the Golconda Sultanate and became an important centre for diamond enhancement, lapidary and trading. Golconda diamonds are graded as Type IIa, formed of pure carbon, are devoid of nitrogen, and are large with high clarity. They are often described as diamonds of the first water, making them among history's most celebrated diamonds. The word "Golconda diamond" became symbolic of diamonds of incomparable quality.
Blue diamond is a type of diamond which exhibits all of the same inherent properties of the mineral except with the additional element of blue color in the stone. They are colored blue by trace amounts of boron that contaminate the crystalline lattice structure. Blue diamonds belong to a subcategory of diamonds called fancy color diamonds, the generic name for diamonds that exhibit intense color.
Larisa Popova is an Italian gemologist, appraiser and jeweler.
