What is a good engagement stone other than a diamond or a birthstone?

She’s not going to wear an engagement ring and a wedding on the same finger, so I want The Wedding Ring to have a diamond. But what then do I put on the engagement ring? My goldsmith recommends against an emerald (her birthstone) since they can be a real pain.

What are some good alternatives?

Garnets are traditional engagements stones in England and Europe; the traditioin dates back centuries and has to do with the deep, red color of the stone, though I can’t remember specifically what it represents. My brother gave his wife an engagement ring with a garnet that they had found while gem-hunting in the mountains. She gets comlements on it constantly.

M57570B Square step cut Emerald Engagement Ring