what are "promotional" diamonds?

Most people have been browsing the newspaper, or see a commercial while watching television, where One-Carat Diamonds are advertised for $500.00.  While that sounds great and many take advantage of these sales, all too many of those buyers eventually come to rue the day they made that fateful decision.  
The bread-and-butter for large jewelry retailers is customer traffic.  Get the customer in the store and you're likely to make a sale.  At least statistics suggest as much.  To attract the customers these large businesses advertise large Diamonds at very low prices.  The only problem is - these are really, really, really, terrible Diamonds.
Promotional Diamonds are the bottom of the barrel.  I3 or worse.   They have but one purpose, get the customer into the store so that, hopefully, they will purchase a more expensive Diamond.  
Aloha Estate Jewelry does not sell "Promotional" Diamonds.  If by happenstance we acquire a single item, within a larger group of jewelry items, that has "Promotional" grade Diamond, that piece of jewelry usually goes to the "Scrap Bag" to eventually be sold for only its gold content.