There are many factors that determine the value of a diamond.
Many purchasers judge a diamond’s price by its size, its colour grade and its clarity grade, but there are many other factors which can affect its price. The way a diamond is cut for example can represent up to 50% of the value of that diamond. Other factors such as fluorescence can make the diamond appear milky. It has been known for some merchants to drill out the natural inclusions in a diamond and to fill the holes with synthetic material. It is important, therefore, to have faith that your jeweller will know about and will disclose these details about your diamond, so you can make an informed choice.
If you have a quote for what appears to be the same item that seems well below all the others, beware! As with most things in life, if it seems too good to be true, it probably is.