The outer ring on these post earrings is made out of bamboo. You'll find multicolored amaranth to shape the tree of life which are preserved in resin.  The posts are made with a silicone/plastic mix and there is no metal on them.  These are great for anyone with metal allergies.  The size can at approximately .30-.45 inches in diameter.  While the multicolor amaranth colors may vary slightly from what is pictured, we'll send you an amazing pair!