Why Buy Diamonds Loose?
First of all, what does “loose” mean. This means that the diamond is unmounted and you can see the 
entire diamond from all sides. Diamonds that are not loose are mounted in a setting or piece of jewelry. This limits the amount of the diamond you can inspect.
It is because diamonds are natural that every diamond is unique and has difference characteristics. Different color, shine and different inclusions. Inclusions are the “imperfections” inside the diamond. These can be black carbon spots, fractures, or even trapped material.
When a diamond is set into a setting these imperfections can be covered by prongs. It is a common practice to cover anything that is coverable with a prong. Why not? If we can make the diamond appear better than it is, by all means, go ahead.
So, the issue now is, is there anything that you are not seeing covered by a prong? Two diamonds may look similar once set, but the value may be a lot different. If one has an inclusion, but it just happens to be coverable. it is worth less than one that does not have an inclusion at all.
If you see the fracture on the side of a diamond and choose to buy it with the intention of covering it, that is your choice. But you should know if there is a coverable inclusion before you but it, and the price should reflect that.
Bottom line, make sure you buy your diamond “loose” or unmounted. You can decide what level of clarity you will be happy with. Don’t get fooled into paying more for a diamond because you didn’t see the inclusion because it was covered.