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Nacre
Nacre is the natural substance produced by mollusks and deposited in microscopic layers around the nucleus to make pearls. It is composed of calcium carbonate and
conchiolin
.
Nailhead
A nailhead is when a round diamond has a dark center resembling the head of a nail, due to a
pavilion depth
greater than 48%.
Natural (N)
A portion of the original surface of a rough diamond left on a diamond usually near the
girdle
.
Near-colorless
This term describes diamonds that appear colorless in a face-up position, but which actually contain slight tints of yellow. Near-colorless diamonds include diamonds in the G, H, I and J color range on the GIA color grading scale.
Needle (Ndl)
A long, thin
crystal
that looks like a tiny rod at 10x magnification.
Nick (Nk)
A small,
chip
-like characteristic with no apparent depth at 10x magnification
Nickel
Nickel is a metal that is
alloyed
with gold to create
white gold
. Most common jewelry allergies are caused by nickel.