Some jewelry items have marking. Is ADL a brand name or an abbreviation for some sort of fake gold?
ADL is one kind of certification on Gold. The full form of it is Antwerp Diamond Laboratory. As you can see from the name it is a laboratory which examines the purity of Gold. And this certification of Gold is famous worldwide. As a result you may often notice their logo on jewelry.
I would say that it’s a name of the brand name, more precisely of the jeweler who created this item, there’s an ADL jewelry group in New York.