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Other Petrified Wood Localities
Petrified wood is not rare. It is found in volcanic deposits and sedimentary rocks at many of locations worldwide. It is sometimes found where volcanic activity covered plant material with ash, mudflows or pyroclastic debris. It is found where wood in sedimentary deposits was replaced by minerals precipitated from groundwater. It is especially abundant around…
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Petrified Forest National Park
The most famous locality for observing petrified wood is Petrified Forest National Park near the community of Holbrook in northeastern Arizona. About 225 million years ago, this area was a lowland with a tropical climate and covered by a dense forest. Rivers flooded by tropical rain storms washed mud and other sediments into the lowlands. Enormous…
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What is Petrified Wood?
Petrified wood is a fossil. It forms when plant material is buried by sediment and protected from decay due to oxygen and organisms. Then, groundwater rich in dissolved solids flows through the sediment, replacing the original plant material with silica, calcite, pyrite, or another inorganic material such as opal. The result is a fossil of the original woody material that…
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Lab-Created Yellow Diamonds
Many of the first attempts to produce diamonds in a laboratory resulted in diamonds with a yellow color. Consider that one nitrogen atom per several thousand carbon atoms can impart an obvious yellow color in a diamond. Then consider that nitrogen is the most abundant gas in the air of the laboratory. It was very…
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Yellow Diamonds and Treatment
Yellow diamonds have been produced by treating brownish diamonds. These treatments include HTHP (high temperature, high pressure), irradiation, annealing and coating. Some of these treatments can be reversed or altered if the diamond is subjected to heating during jewelry repair. Coatings are often thin layers of silica applied to the surface of the stone. These…
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The Incomparable
The Incomparable is a 407.48-carat faceted, fancy brownish-yellow diamond. It is the world’s third-largest faceted diamond, after the Golden Jubilee and the Cullinan I. It measures 53.90 x 35.19 x 28.18 millimeters in size and is cut into a unique triangular shape named a “triolet.” The diamond ended up in the hands of De Beers…
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The Tiffany Yellow
In 1878 one of the largest yellow diamonds ever found was unearthed at the Kimberley Mine in the North Cape Province of South Africa. The rough diamond weighed 287.42 carats and it was purchased by Charles Tiffany, the New York jeweler who founded the world-famous firm of Tiffany and Company in 1837. Tiffany’s gemologist, George…
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The Design and Color of Settings
When buying a yellow diamond for use in jewelry, the color of the metal used in the setting can be important. The first thing to consider is the contrast or harmony of colors that will be present when the diamond is viewed in the setting. The color of the metal can contrast with the diamond…
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“Capes” and “Canaries”
Two common names used for yellow diamonds are “Capes” and “canaries”. The name “Cape” originated in the late 1800s when many diamonds with an obvious yellow color were being produced from mines in the Cape Province of South Africa. They were quickly noticed in the marketplace by diamond professionals who began calling them “Capes” because of…
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The Role of Nitrogen in Yellow Color
Diamonds are composed of carbon atoms, held tightly together in a crystal lattice by strong covalent bonds. When they are composed of pure carbon and are without inclusions or structural defects, they are colorless. Nitrogen atoms are very small and have the ability to substitute for the carbon atoms in diamond’s crystal structure. Trace amounts of nitrogen…