It may not be worth anything
It's incredible how the size of something sometimes is more important than it's worth. For kids, a big toy may be worth more than an expensive one. Sometimes, the size of the gift package leaves the birthday person more excited than its content. For women, the bigger the stone is, the better the ring (or "the bigger the ring, the better"). It may not be worth anything, but the important fact is that everyone can see that she is engaged.