Buying diamond ring is never easy but it will be if you set your priorities right.
Brands, size, colour, clarity, cuts and of cos most importantly your budget.
If your budget is below RM5k and brand is not an issue, first sacrifice on the brands. You may get it from Wah Chan, Tomei, or even other non commercialized shops.
Your next priority will be the size, follows by clarity, cuts and lastly colour. Go for size as you want to have a bigger stone. Better cuts and clarify will give you a more "shiny" stone. Colours not over "I" should be okay. You can't see with a bare eyes on the yellowish if you don't compare eyes to eyes with a better colour grades. After all, size is all matter when she wears it. I hope this will help in your buying. Just my 2 cents.