Diamond prices tend to follow fairly predictable patterns but sometimes, it is not possible for people to charge the market figures. The Rapaport Diamond Price List (referred by professionals as Rap or the List) is the primary source of diamond prices and market information used within the diamond industry.
 
This report has many sheets of price lists which can only be accessed by people with subscriptions and/or professionals.  Checking against the weight (0.01 to 5.99 carats) and shape, subscribers can verify out the prices for different diamonds according to their specifications. Price rises are written in bold while falls are written in bold italics or simple italics. It is important to point out that because the cut, fluorescence, symmetry and polish are not included in the list, there can be variations in the price of the required diamond piece.
  
The diamond prices listed in the Rapaport Diamond Price List are expressed as per carat, in one-hundredth of an American dollar ($100’s per carat). In actuality, may cutters tend to price their diamonds depending on the cost of the rough diamonds, overheads incurred and other related expenses.
The price of the rough diamond usually depends on certain factors:

1. Where is the business deal taking place? Africa, Europe, CIS, USA or any other foreign location?
   
   
2. Where is the physical transfer of rough diamonds going to occur?
   
   
3. What is the prescribed method of payment i.e. wire transfer, C.O.D, cash etc?
   
   
4. Other costs incurred during the purchase such as the travel, hotel, negotiation costs etc.
   
   
5. The crystalline structure of the rough diamond being purchased. It is very important for the buyer to have complete knowledge about the basic structures: stones, shapes, macles, flats and cleavages.
   

Proper classification of the crystalline structure of rough diamonds is the major determinant in the calculation of purchase prices. It is important to note that not all crystalline shapes of diamonds have the same yield. The stone structure yields nearly 50 percent of the finished diamond, the shapes structure yields 45 percent, the cleavages structure typically yields 35 percent, the macles structure tends to yield 28 percent and the flats structure generally yields 25 of the finished diamond.
 
There are a number of websites and companies who offer the services of Rapaport Diamond Price List subscriptions, rough diamond price lists, rough diamond price index and/or rough diamond cost calculators for users. The rough diamond price lists state different prices according to crystalline shape, rough weight, color and clarity. They can also include an image and description of the crystalline structure, the number of finished stones, calculated weight of the polished and finished stone and the maximum values per carat for the rough diamond.
 
A general rule of thumb is that when a diamond is processed, it will lose at least half of its initial weight. This is why processed stones will end up having a price tag double the initial price of the rough cut diamond. The general rule would be that a 1-carat diamond can be created out of a 2-carat rough diamond. Due to advances in technology, modern cutting techniques have allowed the percentage of weight retained to be increased during the cutting process.