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Amethyst Heart Pendant

Amethyst Heart Pendant

Of all quartz varieties, amethyst is the most prized. According to Roman mythology, amethyst was colored purple by the god of wine and was thought to offer protection. The gem derives its name from the Greek word meaning "not to intoxicate." It is now known that just a few iron atoms replacing some of the silicon in quartz causes the purple color. Natural radiation from surrounding rocks where the quartz crystals grew changed these impure atoms into a special form of iron (Fe+4) that absorbs all colors of light except blue and red, which are reflected back to our eyes as amethyst's purple color. The heart-shaped amethyst is mounted in a diamond pendant and weighs approximately 96 carats.

Quartz (variety: Amethyst)

Quartz (variety: Amethyst)

Amethyst is the most prized gem variety of quartz. Just a few atoms of iron replacing some of the silicon in quartz cause the purple color. Amethyst is found in a variety of geologic settings, but the most important is as crystals lining cavities in volcanic rock (geodes). Brazil and Uruguay are the major sources of gem amethyst. However, this amethyst is believed to be from Siberia, Russia. The 56 carat cushion-cut, square-shaped amethyst is set in an 18 karat yellow gold necklace designed by Tiffany & Co. The deep purple color with flashes of red make this amethyst both beautiful and valuable. The floral motif and decorative style of the pendant is a good example of Art Nouveau jewelry that was being made at the turn of the 20th century. Not only is it a remarkable piece of jewelry, but the amethyst gem is much larger than any others in the National Gem Collection from this locality.

Quartz (variety: Amethyst)

Quartz (variety: Amethyst)

Quartz is one of the most abundant minerals in the Earth’s crust. It is composed of the elements silicon and oxygen and in its pure state is colorless. Small amounts of various impurity atoms can produce a range of colors in quartz. Amethyst, the most valuable gem variety of quartz, is purple. Just a few atoms of iron replacing some of the silicon will cause the purple color. This amethyst gem is an intense vivid purple with red flashes. Most gem amethyst is found in Brazil and Uruguay; however, this amethyst was mined in Madagascar. It is the first amethyst gem from Madagascar in the National Gem Collection.

Quartz (variety: Ametrine)

Quartz (variety: Ametrine)

Quartz is one of the most abundant minerals in the Earth's crust. It is composed of the elements silicon and oxygen, and in its pure state is colorless. However, small amounts of various impurity atoms can yield a wide range of colors. Amethyst, the most prized gem variety of quartz, is purple. Citrine is the golden-yellow to orange variety of quartz. The fancy cut gem here is part amethyst and part citrine, known as ametrine. Even though ametrine is a naturally occurring variety of quartz, most ametrine is artificially created by heat treatment and/or radiation of amethyst. The color zoning in ametrine is due to differing oxidation states of iron inside the crystal. Most ametrine is mined in Bolivia, however there are deposits in Brazil and India. This ametrine is a wonderful addition to the National Gem Collection as it beautifully represents some of the state-of-the-art, creative cutting techniques being used today. The Attaway Ametrine, the "Eye of Horus," also illustrates faceting combined with one-of-a-kind gemstone carving.

Quartz (variety: Ametrine)

Quartz (variety: Ametrine)

Quartz is one of the most abundant minerals in the Earth's crust. It is composed of the elements silicon and oxygen, and in its pure state is colorless. However, small amounts of various impurity atoms can yield a wide range of colors. Amethyst, the most prized gem variety of quartz, is purple. Citrine is the golden-yellow to orange variety of quartz. The fancy cut gem here is part amethyst and part citrine, known as ametrine. Even though ametrine is a naturally occurring variety of quartz, most ametrine is artificially created by heat treatment and/or radiation of amethyst. The color zoning in ametrine is due to differing oxidation states of iron inside the crystal. Most ametrine is mined in Bolivia, however there are deposits in Brazil and India. This ametrine is a wonderful addition to the National Gem Collection as it beautifully represents some of the state-of-the-art, creative cutting techniques being used today. The Dyber Ametrine incorporates "Dyber Optic Dishes" creating optical illusions and is faceted and carved by hand.

Quartz (variety: Chalcedony)

Quartz (variety: Chalcedony)

A whimsical collection of over 1,000 "picture" agates was gifted to the National Gem Collection in 2007. Chalcedony is the general name used for all fibrous-textured varieties of fine-grained quartz. Agate is probably the most familiar type of chalcedony and typically comes in shades of white, gray, yellowish-brown to reddish-brown. The colors are mostly caused by small crystals of iron and manganese oxide minerals in the chalcedony. These picture agates were found in the Indonesian provinces of Java and Sumatra. The agates are hand-cut en cabochon and polished to retain the natural patterns that resemble a wide variety of objects, such as letters of the alphabet, numbers, crosses, and other images such as fish, hearts, and Ying Yang symbols. The agates are natural and have not been treated, heated, or chemically enhanced.

Quartz (variety: Rock Crystal)

Quartz (variety: Rock Crystal)

This 7, 478 carat faceted (240 facets) quartz egg, created by John Sinkankas, originated in Brazil. The metal base is set with 16 small and 4 larger sapphires. Under ideal conditions, in spacious cavities or other openings in rock, quartz crystals can grow impressively large, sometimes weighing several tons. Clear colorless quartz, called rock crystal, is the most common gem mineral. Most commonly, rock crystal is used for carvings, chandeliers, and crystal balls. This quartz egg is an outstanding example of the gem cutter's art and is the largest faceted quartz in the National Gem Collection.

Quartz Gems

Quartz Gems

This assortment of quartz gems exhibits a variety of cutting styles and includes amethyst (purple), rose quartz (pink), citrine (gold-orange-yellow), smoky quartz (brown-gray-black), rock crystal (colorless), and ametrine (part amethyst/part citrine - bi-color). The largest gem, the shield-shaped citrine (center top), is 636.55 carats. Most of these quartz gems are from Brazil, however some are from Bolivia (two ametrines), Switerzland (smoky quartz), and the U.S. (octagonal cut amethyst).

Quartz with Anatase

Quartz with Anatase

It is common to find inclusions in quartz crystals. Quartz is usually one of the last minerals to form in a deposit, so it sometimes grows around existing crystals. Because quartz is commonly clear, the inclusions are easy to see. This emerald–cut quartz from Brazil has a blue anatase crystal inclusion as well as needle-like inclusions of rutile. In this specimen, we can see the anatase inclusion seemingly floating in this clear quartz gem. Anatase is a form of titanium dioxide and is usually found as small, isolated, well-developed crystals. This is the first quartz gemstone with an anatase inclusion in the National Gem Collection.


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