Each organically shaped ring is handmade from recycled Argentium (935) silver and is one-of-a-kind. The Sapphire River Rock has a 3.5mm sapphire and is rectangularly shaped- approximately 3/4 inch long and 1/2 inch wide, size 8. The Tsavorite Garnet River Rock has a 3.0 mm green garnet and is circular- approximately 5/8 inch, size 8.25. Because of their low profile top and comfortable band, this style is great for every day because it's so comfortable to wear. Argentium silver is a modern silver alloy similar in appearance to sterling but is tarnish resistant. The rings are named after the rocks that you see that you can't help but pick up, because they've been worn so smooth, almost symmetrical, and more beautiful over time. Choose gem at checkout. In stock and ready to ship within the U.S. only.