rubies and sapphires. Price per carat:$51-$108.08 Highlights: Amblygonite is usually a light straw color, but it occasionally displays more vibrant shades of yellow, green, blue-green and even lilac.

This 3.28-carat Paraíba tourmaline's vivid violetish blue hue rivals the finest sapphires. Because of this tourmaline's rarity, its per-carat price is also likely to rival the price of fine sapphire.

Sapphire comes in a variety of colors. This rare 1,126.00-ct. corundum crystal ... another corundum variety. Besides blue sapphire and ruby, the corundum family also includes so-called “fancy ...