4 G's should buy you a nice vs1 or vs2 stone g-h-i color range in the 1 to 1.25 carat range if you educate yourself and do some shopping around and negotiaing.
Check out this site -
www.diamondcuttersintl.com
Also read book - How to Buy a Diamond by Fred Cueller
You may be able to get book free off the website if they still do it.
hope this helps
good luck.