Joel A. Bartsch has been active with the Houston Museum of Natural Science (HMNS) as a curator over the past three decades. As CEO and president, Joel A. Bartsch oversees a collection that encompasses 450 treasures of the mineral world brought together in the Cullen Hall of Gems and Minerals.
One unique aspect of the permanent exhibit is a stone cutter who sometimes demonstrates how facets are created in rough specimens of gemstones such as star ruby and malachite.
There are two basic gemstone types, with cabochons formed into a dome-like shape with a flat bottom. This technique is most suitable for opaque specimens and showcases the unique quality of gems such as moonstone and opal to their fullest. Instead of brilliance, luster, color, and texture are brought out in a stone, often affixed to a ring, necklace, or pendant.
By contrast, faceted stones are generally transparent and cut in symmetrical patterns from a variety of angles. Each small flat surface is known as a facet and contributes to intricate reflections on the outside of the stone and light refraction inside the stone.
Facet cutting is an art form with a centuries’ long history, and there is a myriad of geometrical arrangements possible. A basic step-cut creates an octagonal form through rectangular steps that parallel one another. The brilliant cut makes a rounded whole, with cone-, triangle-, and kite-shaped facets moving outward from the gem’s center. Mixed cuts seamlessly combine brilliant and step cuts in unique combinations that maximize light interplay.
One unique aspect of the permanent exhibit is a stone cutter who sometimes demonstrates how facets are created in rough specimens of gemstones such as star ruby and malachite.
There are two basic gemstone types, with cabochons formed into a dome-like shape with a flat bottom. This technique is most suitable for opaque specimens and showcases the unique quality of gems such as moonstone and opal to their fullest. Instead of brilliance, luster, color, and texture are brought out in a stone, often affixed to a ring, necklace, or pendant.
By contrast, faceted stones are generally transparent and cut in symmetrical patterns from a variety of angles. Each small flat surface is known as a facet and contributes to intricate reflections on the outside of the stone and light refraction inside the stone.
Facet cutting is an art form with a centuries’ long history, and there is a myriad of geometrical arrangements possible. A basic step-cut creates an octagonal form through rectangular steps that parallel one another. The brilliant cut makes a rounded whole, with cone-, triangle-, and kite-shaped facets moving outward from the gem’s center. Mixed cuts seamlessly combine brilliant and step cuts in unique combinations that maximize light interplay.
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