Lignum nephriticum cup crafted from narra wood (the namesake in the province) manufactured opalescent hues when water is poured into it. These wood cups were being a major pre-colonial and colonial marketplace of Naga. Naga is the native pre-colonial name of the city. It's named following the narra tree https://jeffreyxkwhr.frewwebs.com/28711385/top-23naga-secrets