Editing Diamond cutting (section)

=====Weight retention=====
The weight retention analysis studies the diamond rough to find the best combination of finished stones as it relates to ''per carat'' value. For instance, a 2.20-carat (440&nbsp;mg) octahedron may produce (i) either two half-carat (100&nbsp;mg) diamonds whose combined value may be higher than that of (ii) a 0.80-carat (160&nbsp;mg) diamond plus a 0.30-carat (60&nbsp;mg) diamond that could be cut from the same rough diamond.

The round brilliant cut and square brilliant cuts are preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals, such as [[macle]]s are more likely to be cut in a ''fancy cut''—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.

Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight, about 50%.<ref name=x50>{{cite book |url=https://books.google.com/books?id=jPT6JADCqgwC&pg=PA280 |page=280 |title=Handbook of carbon, graphite, diamond, and fullerenes: properties, processing, and applications |author=Pierson, Hugh O. |publisher=William Andrew |year=1993|isbn=0-8155-1339-9}}</ref> Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the weight. Since the per-carat price of a diamond shifts around key milestones (such as 1.00 carat), many one-carat (200&nbsp;mg) diamonds are the result of compromising ''cut quality'' for ''carat weight''.