Other things to consider when making that special purchase...

Quality : Many jewelers offer guarantees, not so much as a type of warranty, but as a way of assuring that the stone being purchased is everything it clams to be. This is often coined as a CERTIFIED DIAMOND. in many cases, the ring will be accompanied by documentation in the form of a certificate. It spells out in detail the particulars of all the dimensions of the stone.

Financing : Most companies offer financing for such purchases. Often times, dependent on credit score, jewelers will offer any where from $500 to $5,000 dollars or better. This may guide you as far as what path to take when considering gem size.