Some people (including me) care if their jewel colors coordinate in items, or that the jewel color feels appropriate for the effect the jewel has. You may get better offers if you have, for example, a w/hite or blue cold Rainbow Facet (yes really). It's in your best interest to post the color.
(Brought to you by a frustrating two days of asking what color jewels are in trades)

Karew
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