A diamond on memorandum is one that’s borrowed from a supplier for the retailer or wholesaler to show, and hopefully sell, during a short period of time. If it doesn’t sell, it is promptly returned. For example, a potential client calls and asks if you have a 1.00 ct. RB H SI1. You respond by saying that you don’t have it on hand, but you have a source for such a stone and can get it in overnight. You call the customer to let him know that the diamond has arrived and set up an appointment for viewing it. You show the diamond and the customer decides against it. You now return the stone to your source without obligation except for probable shipping charges.