I am very glad that my wife was reasonable and agreed that I need not get her a diamond. She still wanted a ring, so I designed and made a claddagh style ring for her, with a blue topaz set in silver. It cost me less than $50, plus many hours researching, designing, and carving the wax mold. (I have a friend who is a jeweler, and he was able to provide expert assistance and tools to get the job done :)
Now, rather than bragging about how big and expensive the stone is, my wife happily shows off her ring and tells her girlfriends how I made it for her, and how beautiful and special it is.
My wife is the most awesome woman ever! (Source: Personal experience and careful study and observation).