In the strictest definition, chemically, diamonds do not effervesce -- give off gas. However, visually, one could describe a diamond as vivacious, which is another definition of the word you wrote.
In the 1700s, Lavoisier proved that diamonds are carbon only, by burning one and analysing the gas to show that it was CO2. Therefore the diamond was carbon. Yellow diamonds have a contamination of...
The phrase "diamond accents" in the description of a piece of jewelery generally refers to small diamonds. Often they're so small you'd need a magnifying glass to tell that they actually are there.
There is a famous diamond, described below, that was known as 'The Austrian Diamond' at one time. This diamond was a fancy yellow stone, originally dealt into European Royalty by the same French...