Tungsten, Titanium and Ceramic Rings Set with Hawaiian Koa Wood, Abalone Shell and more. Hawaiian Koa Wood has been treasured for years. It has been used for outrigger canoes, paddles, boxes, furniture and now rings, it is an excellent toned wood which produces a rich warm sound and is used also for Ukuleles. Supply of Koa is getting scarce and just recently Hawaiians have been replanting their Hawaiian Koa Wood Trees. Koa is renowned for its iridescent shimmer and luscious color which ranges from tan to warm gold with brown and black accents.