As a Christmas present, I was asked to make a pair of crosses for husband and wife each engraved with their names and date of their wedding. So far, so good.
There was a further requirement that the two crosses could be worn together. This was achieved by having silightly different chain rings, both offset to the rear. Gravity then causes the two to hang together. Simple idea, but requiring more precision than normal for me!
The crosses are both hallmarked on their rear face.