I've been looking up all the family crests, and symbols. So I think that's what the gems are fashioned after like they bare the color, and mark of the family crest. Also I think the guantlet Titan was referring to holds the artifacts inside it. Sort of like a digivice from the second season where it held all the armor eggs. 

Edit: I don't really know what the purpose of the gem is. But, I'm pretty sure its significant.