- Laser Drill Hole - A hole made in a diamond by laser drilling.
This technique is used to reach a black pique in order to bleach it (with acid) and improve the look and clarity of the stone. However, as this is a treatment, it materially (negatively) impacts the value of the diamonds.
- Laser Inscription - labs inscribe the grading report or certificate number on a diamond's girdle.
Using a laser, labs can inscribe the grading report or certificate number (or client reference) on a diamond’s girdle. This has no impact on the diamond’s value, but makes it easier to identify the diamond.
- Lizard Skin - wavy area on the surface of the diamond (that looks like lizard skin!)
Bumpy and imperfect texture on the surface of a cut and polished diamond.
- Loupe - a small, handheld magnifying glass used to view diamonds.
A 10x loupe is standard, but other powers are available (14x, 20x, etc.). Gemologists use loupes to inspect stones in more detail. By magnifying the diamond or gemstone, they are able to spot any potential inclusions or blemishes in the stone. It is important to look at stones in this level of detail so as to accurately assess, grade and value a diamond. Tiny imperfections can have a big impact on how much a gemstone is worth.
- Lower Girdle Facet - Triangular facets just below the girdle.
The lower side of a round diamond is made up of the pavilion and the lower girdle facets. Lower girdle facets, also known as lower halves, determine how much contract the diamond has.
- Luster - the quality of shining by reflecting light from the surface of a diamond.
Rough diamonds have a “greasy” luster, whereas cut and polished diamonds have fantastic luster.
There are many terms used to describe luster, these include: adamantine, metallic, vitreous, greasy, dull and resinous. Adamantine means that the stone displays fantastic brilliance and is most notably seen in cut and polished diamonds.