There was a time when gem cutters sliced the gemstones as cabochons. The concave cut gemstones have always been very popular since 12th century when the concept of faceted rocks came into the picture. Improved machining tools and techniques since 16th century made it possible for the gem cutters to develop horizontal cutting wheel that created elaborate designs and geometric schemes. Concave cut gemstones in recent times have been produced using 3-dimensional LASER Cutting tools for precision touch.
Here are 5 enticing facts about the gemstone cutting technology used to manufacture them.
The Technology: Concave gemstones in facet cut
The flat symmetrical cut made on the gemstones to achieve 58 facets was always in a vogue. Richard Homer redefined the way gems could be cut to create brilliant effects. Though Homer is believed to be the father of concave cut gemstone idea, it was American lapidary artist Douglas Hoffman patented the technology of producing concave cut gemstones using 3-D.
Concave cut: Why it is made
The gemstone is cut into cone-shaped with 3-d facets with a distinct length and breadth on the surface. The pavilion facets are often cut in concave curves with flat facets sitting over the crown. It results in brilliant reflective patterns, particularly when the gemstone is viewed from top.
One of the advantages of cutting the gem into concave shape is that the light is evenly reflected through it. It creates a homogenous effect unlike any other cut. The glow exudes from the internal structure and radiates a more uniform blush.
Moreover, the concave cut is a 3-D cutting method. It results in equal radiance when viewed from all angles. It creates depth on the conical facet of the gem resulting in added brilliance and alacrity from commercial point of view. Using the concave facet cutting technique minimizes hot spots from appearing when manufacturing fancy shapes like opal, pear and marquise. It is also the best way to eliminate the colour zoning effect that often mars the light coloured gemstones of bigger size.
Third advantage of having a gemstone cut in concave pattern is that even the smallest of light falling on it is exuded brilliantly. It automatically translates to higher likeability.
Cost of cutting a gemstone in concave style is more economical and time-saving than other methods.
Limitations of using concave cuts
Not all gemstones available in the market are suitable for concave cut. As a thumb-rule, only large sized concave gemstones are known to emit brilliant results when compared to the smaller ones. Also, if the gemstone is light in colour, it is preferred for concave cut over darker shades. Mathematically, using the concave facet cut enhances the colour tone by 25 percent.
Gemstones that transform beautifully when given a concave cut are:
Gemstones that are least preferred for this cut are:
- Red Spinel
As expertise improves, concave gemstones are likely to rule the market in coming years.