Learn the four C's (Cut, Carat, Color, Clarity). When you have chosen the shape of the diamond do a little research on the length to width ratio's, depth and table percentage. Out of the four C's Cut is by far the most complicated. Learn how to read a grading report. Take your time and don't let anyone rush you into a purchase. Here is a quick diamond educational video.
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Hope this help
Andrew
HerDiamondEngagementRing.com
www.youtube.com
Hope this help
Andrew
HerDiamondEngagementRing.com