It would help if PM bracelet links were hallmarked

[Zsprings]

The odd thing is that even some jewelry salespeople I've spoken to, think white gold on a ring is a finish which can be removed. But it is of course an alloy of gold (all the way through).
As the some of links with a Rolex bracelet are removable, then surely those individual separate links might be stamped '750' or have a hallmark. Who is to say when buying pre owned, the separate links are gold alloy and with white gold that they are not removable stainless steel links? Checking online how to determine if an object is gold, it is suggested a drop of vinegar on the metal, no change on under the droplet, the metal is gold.