The effect of the lighting environment was well understood by jewelers in the late 1800s. Minimal grading standards at the time included  “good north light unobstructed by buildings or other objects”, grading between the hours of 10am and 2pm only, no use of artificial light, and use of the same location for grading (amongst others that are less important to this story). 

Synthetic diamonds are grown in a laboratory and have essentially the same chemical composition and crystal structure as natural diamonds formed millions of years ago. In the last 30 years, gem quality synthetic diamonds have been grown in Japan, South Africa, Russia, Ukraine and the United States. Synthetic diamonds are generally produced using either High Pressure/High Temperature (HPHT) or Chemical Vapor Deposition (CVD).