Men's 4-Carat Emerald-Cut Lab-Created Blue Sapphire 18k Yellow Gold over Sterling Silver Ring Top Rated Seller - Trusted Since 1952 - 90 Day Guarantee - Easy Returns - Free PalmBeach Jewelry Gift Box 18k Yellow Gold Over Sterling Silver - Quality Stamp (.925) Sapphire is a precious gemstone available in an array of colors, most popular in a hue of deep blue. Ring Style: Classic - Theme: Nuggets and Bling Handsome octagon-cut lab-created blue sapphire ring. 4 carats. The main stone is framed with a sparkling diamond accent on each side. An understated sign of his success. 18k gold over sterling silver. Sizes 8-13. (All carat weights are approximate and may vary slightly from those listed.)