If a diamond engagement ring was stolen from your house how long will it take for your insurance company to send a check for a new ring?

First off, very sorry to hear that that happened. An engagement ring holds a great deal of sentimental value, so to loose it in such a way is awful.
I actually don't know how long it takes for insurance co's on average to cover for something like a lost/stolen ring, however I do have a very helpful piece of advice to consider for when you get your replacement ring -
Make certain that your ring comes with a GIA (gemological institute of america) grading report. GIA created the 4Cs that I'm sure you know all about (color, carat, clarity, cut) - and they're an independent, nonprofit organization created with the interest of the consumer in mind. GIA is recognized as the ultimate authority on gemology by the jewelry industry and the U.S. government; providing consumers with unbiased, accurate, astute, scientific evaluations of diamonds based on the mentioned 4Cs.
And this doesn't apply just for engagement rings - any piece of "gem'd" jewelry that you are looking into purchasing should be purchased with a grading report.
Ultimately, I'm telling you this b/c by having a grading report from GIA, most insurance companies are quick to provide coverage because GIA is so well known and well respected in the industry. You can check them out online @ http://gia4cs.gia.edu/
Cheers, Rich ?
Depends on the insurance company and the circumstances surrounding the loss. //