Tweetif thats what you want then go for it.....as far as how much, i dont know her but spend what you think is right, never been shopping for engagement rings so i have no clue what they cost.....my dad bought my mom a gigantic diamond ring for their 30th anniversary because when they got married he didnt have alot of money, fresh out of college and the army but he spent more on that ring then some people make in a year. Point being fuck it spend what you can afford now and if she loves you she will be around for you to buy her more in the future.