This is a very beatiful design work of a Ring which can be prepared with Amethyst or other sort of gem. White gems are diamonds.On a pictures You can review the prepared version in gold 18k with diamonds.
Also watch the video.
The max weight for 18k is approx 6-7 gr (only metal weight)The total weight of gems is approx 1.0-1.2 ctThe weight of central big Colored gem is approx 16 ct