Different people prefer different type of lighting when observe gems. Most of gemstone dealers prefer sunlight when examine gemstones. A problem occurs when purchasing gemstone at jewelry fair because of different type of lighting in decorating the booth affect the way buyers look at the stone.
I personally made one mistake when purchase rubies during the show. After I purchased I looked at the stones again in my office, The color of stones turned out to be quite different from what I saw at the show. Several of people, I know may avoid to buy gemstone at the fair because of this type of problem. They prefer to let dealer bring goods to the office and see in their prefer lighting environment. I personally think this type of problem cannot completely resolve. For me, I have to prepare my own lighting as well as sample of gemstone color whenever I purchase the gemstone everywhere.
The following pictures illustrate one Africa flux fracture healing ruby, size 29.72 ct, in three different type of lightnings. The first picture, the stone expose in a daylight lamp.
The second picture is the same stone expose in a florescent lamp.
The last picture is the same stone under sunlight.