Can diamonds be used to ack up a digital currnency like gold is?

I came across an article talking about a new digital currency being backed by gold. I'm sorry I didn't bookmark it but a quick google search will help you find it if you haven't heard about it yet. Anyway I want to know, can this be done with diamonds? If so how exactly do we know how much a diamond is worth? Are diamonds even worth any real value? Well I get that industrial diamonds are( those used on drill tips), But what about those used for jewelry?