When choosing an emerald necklace, focus on three key qualities:
1. Color: This is the most important factor. The most prized emeralds have a deep, vivid green color, sometimes with a slight bluish hue.
2. Clarity: It is natural for emeralds to have inclusions, often called "jardin" (garden). These are accepted as part of the stone's unique character, as long as they don't impact its overall beauty.
3. Cut: A well-executed cut, most famously the rectangular "emerald cut," will maximize the gem's rich color and brilliance.