One other thing before moving to color and clarity:
Total carat weight is not the same as carat weight when it comes to loan value. Jewelers always have pieces with a relatively small center diamond such as a third of a carat and with lots of small side diamonds. The total carat weight of the piece may be a 1.00 or even 1.50 carat or more. The small side diamonds usually have no loan value at all. It costs more to set them than to buy them. So the loan value of the piece will be the loan value of the 0.33 carat (e.g.) center diamond, which could be as little as $150. The customer may have paid $2000 to $3000 for the piece and thinks they have a 1.50 carat diamond ring that should be very valuable as collateral on a loan. But having all the carat weight in a single stone is what maximizes the loan value of the piece of jewelry.