Since the late 1800s, scientists from all over the world attempted to reproduce diamonds in laboratories. It wasn’t until 1955 that General Electrics was able to produce the first diamond. The diamonds produced however, were too small and not of gem quality. It wasn’t until only a few years ago that technology reached a point capable of producing larger diamonds that were gem quality.
A mined diamond is created by the same method of heat and pressure as a lab grown diamond. Nature just happens to do it over a much longer period of time.
Both mined and Lab grown diamonds share the exact same chemical composition, molecular structure, physical and optical properties - a statement which simply cannot be said for any form of diamond simulant or imitation. Diamond is a solid form of pure carbon. Solid carbon can occur in different forms (known as allotropes) depending on their type of chemical bond. An allotropic, solid form of pure carbon with its atoms arranged in a crystalline form, diamonds are the only gem made up of a single element; typically about 99.95% carbon. This applies to diamonds both mined and Lab grown.
(The other 0.05% may include trace elements, atoms that are not integral to nor a part of the essential chemistry of a diamond. These trace elements (e.g. boron, nitrogen) as well as other natural occurrences such as radiation exposure, can have an influence on the shape or colour of a diamond).