Vulcan gong

From Memory Alpha, the free Star Trek reference

The Vulcan gong is an ancient Vulcan musical instrument.

It is hexagonal in shape and made of an unknown metal. It is struck with a hammer that is partially made from a green stone.

During a Vulcan wedding ceremony, it is customary for the groom to call the wedding party by striking the Vulcan gong. (TOS: "Amok Time")

A similar gong was rung during Spock's Fal-tor-pan ceremony in 2285. (Star Trek III: The Search for Spock)