Natural Vintage Hawaiian Puka Shell Necklace 16 1/2" long

Vintage 1970s Hawaiian puka shell necklace. The shells are natural with natural holes. Well bleached by the sun, pitted and smoothed by the ocean and sand. They are 5.3 mm diameter. Necklace is 16 1/2" long. Weight: 25.2 grams. Original costume grade clasp. Need to be cleaned.