The carat weight of a gemstone does not necessarily allow you to accurately envision the size of the gemstone. Different gemstones have different densities (mass per unit volume), so two gems that appear to be the same size may actually have very different weights. For example, a ruby is more dense than a diamond, so a 1-carat ruby will look smaller than a 1-carat diamond.
Always request the dimensions of a gemstone to ensure that the majority of the gemstone weight will be visible when set in the setting.
To help you envision the gemstone's actual appearance, we at Blue Nile provide the diameter dimensions (for round) or length and width (for other shapes) of a given gemstone. You can even click the zoom button to see a closer look at any piece of gemstone jewelry.