[header] How to shop for emeralds [title] Consider the emerald's hue. [step] Hue refers to the purity of an emerald's color, and it is one of three points to consider regarding color quality. Most emeralds have a blue-green tint, while others may have a yellow-green tint. 
The most valuable have strong color, and are as pure green as possible without becoming dark. [title] Look for a deep tonal color.