When I was growing up on the North Shore, I always tried to be the first person on the beach in the early morning so I could have first dibs at the beach glass scattered across the sand. Our family beach-glass rules were strict: no see-through pieces, no jagged edges; those did not qualify as beach glass yet and were to be thrown back in the ocean to be polished to perfection by the sand, the sea, and time. In the '60s, I could often find a dozen pieces in a given morning; by the late '70s, when I walked the beach with my son, Duncan, we seldom found more than a piece or two. By the late '90s, a tiny sliver of beach glass was a rare find. Now beach glass seems to have disappeared from our stretch of sand near Laniakea.

During the first decade we lived at the beach house, the family collected enough beach glass to fill two 3-foot high apothecary jars. To fill those now would take a lifetime, and a lifetime may not be long enough. Beach glass has become increasingly rare on O'ahu's beaches. Now, it seems, these frosted gems may be endangered.

In the August issue of National Geographic magazine, writer Margaret G. Zackowitz says we can blame the disappearance of beach glass on the arrival of plastic. She quotes Mary Beth Beuke, president of the North American Sea Glass Association: "We're at the end of the sea glass window. ... There is less glass packaging now and more recycling."

Of course, Zackowitz points out, beach glass "started out as something not worth keeping. Trash tossed off ships or washed from dumps must spend years in the water to become good sea glass. Wave churn, shore terrain, water acidity and composition of the glass itself all play a part in creating the smoothed shards' characteristic matte texture."

My family feels fortunate to have a treasure from the sea that my parents found on the beach at Punalu'u on their honeymoon in 1940: a lavender glass ball, 14 inches in diameter. They always joked that if it ever broke, they would divorce. Needless to say, it is still intact and more beautiful — and rare — than ever.