All diamonds are weighed in metric carats. Carats are divided up in a similar way to a British pound. For example in every pound there is one hundred pence. For example a 0.75pt diamond will be a 0.75ct which is 0.75pt out of one carat. The common misconception with carat is that this refers to the actual physical size of the diamond. It in fact just refers to the weight of the diamond when it is on the scales. The physical size is determined by other factors from the 4c's. When diamonds are weighed it is usually done to the most accurate hundred thousandth. The reason for this is a point either way can alter the cost.
We always suggest trying different carat weights on to see which is the best for you. Many of our customers have started of looking at a 0.40ct diamond and ended up leaving with a much bigger diamond mainly due to the bigger size sitting much better on their finger.
If you are ever in doubt about carat weight please feel free to contact us and one of our diamond experts will explain this to you in more detail.