Closing Windows on Faceted Gemstones
When a gemstone is cut to improper angles it can allow light to 'leak' through the center of the stone and lose some of its color and brilliance.
This ia a very common factor in gemstones which have been cut overseas. They cut to "save weight" rather than cutting for brilliance. Many gem dealers will buy their gemstones overseas and then have us re-cut them to "close" the window and make the gem more brilliant.
Below our photo gallery you will see more answers to your questions about closing windows on faceted gemstones.
See examples below of Gems we have Re-cut to Close their Windows
How do you close the window? Brilliance is a factor of the geometry of a gemstone. If the angles on the lowest facets of the pavilion of a gemstone are "too shallow", then the light will leak through the bottom of the gem rather than "reflecting back" to the eye.
To remedy this situation, we measure the length and width of the gemstone and also the angles on the pavilion and then re-facet the pavilion to proper angles.
Because of the geometry, it may be necessary to make your gemstone 'narrower', reducing the width of the gemstone, in order to close the window. But that may not be necessary. Many times we can close a window without reducing the width at all.
Will re-cutting increase the value of my gem? From what I have observed and some gem dealers have told me, when one takes into consideration the following factors, a) After re-faceting there is an increase in the per carat value of the gem, b) There is some weight loss due to re-faceting, c) The cost of the re-cutting. The net result is about break even.
They tell me they have the gems re-faceted because the gems sell faster when they are more brilliant and more colorful.
Denton Anderson,
Gemologist & Gem Cutter
click photo for Video
Graduate Gemologist, GIA, GG
Over 20 years of experience.
