They hurried along with all the speed they could make, and after a mile or two they saw the Last Bridge ahead, at the bottom of a short steep slope. They dreaded to see black figures waiting there, but they saw none. Strider made them take cover in a thicket at the side of the Road, while he went forward to explore.
Before long he came hurrying back. 'I can see no sign of the enemy,' he said, 'and I wonder very much what that means. But I have found something very strange.'
He held out his hand, and showed a single pale-green jewel. 'I found it in the mud in the middle of the Bridge,' he said. 'It is a beryl, an elf-stone. Whether it was set there, or let fall by chance, I cannot say; but it brings hope to me. I will take it as a sign that we may pass the Bridge; but beyond that I dare not keep to the Road, without some clearer token.'
[Glorfindel said] 'It was my lot to take the Road, and I came to the Bridge of Mitheithel, and left a token there, nigh on seven days ago. Three of the servants of Sauron were upon the Bridge, but they withdrew and I pursued them westward. (...)'
J.R.R. Tolkien Lord of the Rings - The Fellowship of the Ring
Yes, our Hope Tokens are made of Beryls! :D