Carat Weight
Generally speaking, the heavier precious gemstones are, the more expensive they are. Rubies are the exception. High quality rubies weighing less than 3 carats will be of higher value than big rubies weighing around one hundred carats with low clarity. One reason for this is the difficulty in cutting big rubies due to the inclusions that are present. Buy these rubies directly online:
1 carat (Ø5.8-6.4mm)
1.5 carat (Ø6.3-7.1mm)
2 carats (Ø7.0-7.6mm)