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CVD, HPHT and Natural Diamonds
Article
Is There a Difference Between Natural and Laboratory-Grown Diamonds?

Learn about the differences – and similarities – between natural and laboratory-grown diamonds, and how GIA’s researchers and grading laboratories can tell the difference

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A bright orange, multi-faceted gem.
Article
Fall for Autumn Gems

Nature gives us a brilliant palette of color-changing leaves and a spectacular kaleidoscope of colorful sunsets during the fall season.

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A heart-shaped piece of pink drusy hangs from a gold chain.
Article
Dreamy Drusy: Minute Crystals Shimmer in Dramatic Designs

Drusy jewelry has surged in popularity in recent years. Celebrities wear it on the red carpet and designers clamor for it at gem shows.

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Bursts of yellow and purple radiate throughout this round cut amertrine.
Article
Colorblocking: The Art and Fashion of Multicolor Gemstones

The fashion trend of colorblocking can be found in the artistic combinations of color in multicolor gemstones known for their color zoning or banding.

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Looking down the crystal axis of a backlit 58.83 ct trapiche emerald
Article
Emerald: The Superstar of Trapiche Gemstones

Trapiche emeralds, which display a distinct six-spoke wheel pattern, set the standard as some of the finest and most spectacular crystals unearthed.

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Interference figures in faceted alexandrite
Pleochroism and Color Change in Faceted Alexandrite: Influence of Cut and Sample Orientation

Shows how alexandrite’s color and color change are affected by cut and the orientation of table facets.

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Six-rayed stars in a yellow sapphire.
Star-Like Growth in Natural Yellow Sapphire

A natural yellow sapphire features a distinctive star-like graining pattern.

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Rough diamond, yellow in color
Article
Diamond Research Gives Clues to the Formation of the Continents

Mineral inclusions trapped in diamonds reveal the continents’ construction – and helps GIA researchers date diamonds.

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Color-change diaspore
The Color Origin of Gem Diaspore: Correlation to Corundum

Examines the color origin of color-change diaspore, known commercially as Zultanite, and compare the effectiveness of the chromophores it shares in common with corundum.

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A blue synthetic star sapphire from past production of Wiede’s Carbidwerk
Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany

Details the process used by Wiede’s Carbidwerk to produce star synthetic corundum from the mid-1950s through the 1970s.

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