The outer ring is hand-sliced bamboo with white (natural colored) sesame seeds and dyed amaranth preserved in resin.  The posts are hypo-allergenic nickel-free surgical steel.  They are approximately 3/4 - 1 inch in diameter.  Please note that the center amaranth color will be artist choice!  We'll ship you an amazing pair!  If you have a specific color request, please contact us prior to purchasing.