Micro-World Gems & Gemology, Summer 2017, Vol. 53, No. 2

Christmas Tree–Shaped Internal Feature In Diamond

LMR in diamond viewed with different illuminations.
Left: A 3.32 ct fancy-color diamond hosts a laser manufacturing remnant of unusual shape; here, it is seen with diffused fiber-optic illumination. Right: Rheinberg illumination accentuates the LMR’s resemblance to an evergreen tree. Photomicrographs by Jonathan Muyal; field of view 2.90 mm.

A 3.32 ct Fancy yellow marquise diamond recently submitted to GIA’s Carlsbad laboratory for color origin determination was of particular interest for its large, eye-visible laser manufacturing remnant (LMR). This LMR extended along a relatively straight path from a star facet through the pavilion and featured lily pad stress fractures stacked in parallel along its length, a composition reminiscent of a Christmas tree preserved within the diamond. With its resulting “green foliage” against a dark blue night, the use of Rheinberg color contrast illumination technique (N. Renfro,“Digital photomicrography for gemologists,” Summer 2015 G&G, pp. 144–159; Fall 2015 Micro-World, pp. 328–329) dramatically accentuated this already evocative scene (see above).

Unlike the remnants of laser drilling used to remove small inclusions, LMRs are an unintended consequence of either carelessness or unpredictable laser optics. As such, they are graded as clarity characteristics that can reduce the overall quality and value of a diamond. LMRs can occur during the laser cutting of a diamond. They appear in a variety of shapes but often resemble the remnants of internal laser drilling (Fall 2013 Lab Notes, p. 174).

Ironically, an accidental feature that might otherwise downgrade a diamond’s value can have a positive outcome. This unique and aesthetically pleasing internal feature has created an interesting collector’s gemstone, a perfect gift for the Christmas season!

Jonathan Muyal is a staff gemologist, and Troy Ardon is a staff gemologist with a focus on color origin, at GIA in Carlsbad, California.