Want to buy a ring

Hi, i'm feeling very panicked. I have a mental plan for purchasing an engagement ring I know I can afford. I have enough for a great down payment and enough to to fulfill the 1 year plan the jewelery store offers in probably 9 months, so even better. My concern is actually applying. Up until recently, I had no revolving credit. I got two new low limit cards from cap 1 and orchard bank, but they won't even start reporting until july 1. So that may not help me. I have 3 old collections, paid, that i've had no luck in deleting via good will letters. Other than that i have current student loans and car payment, albeit the car is less than a year old. So i'm really worried given that i know how much trouble i had getting the car loan. What stinks is i'm not going in to debt for this ring. I'd do layaway but i don't want to wait a year to get engaged.

So are jewelery stores easy to work with? I called around and they gave me the same rundown you get anywhere about what they look for in credit. Would a co-signer help? I look at sites like Who Gave Me Credit and see people with much lower scores getting credit at places like Kay, but i know i was declined at Helzberg not long ago, so i don't want to apply unless i'm comfortable. Would my down payment help me get approved?

Please offer me any advice!