For centuries, scientists all over the world have searched for clues relative to the nature of the processes and conditions that are necessary for the development of minerals, including gems. Some important answers came with the discovery of methods for synthesising gemmiferous materials in the laboratory. From these aimed experiments, scientists were able to determine the three factors necessary for the formulation of gemmiferous material: chemical elements, temperature, pressure.
The type of gem that is able to form in a given location is determined by the primary materials present in that environment. For example, quartz, whose chemical formula is SiO2, can only form where the elements silica and oxygen are present. And since these elements constitute over 74% of the weight of the Earth’s crust, it is not surprising that there is an abundance of quartz at any given place on the planet. It is, however, rare to find gem-quality quartz.
Even if the necessary chemical elements are present in the environment, relative temperature and pressure conditions must be correctly balanced in order for a particular gem to form. If this is not the case, a somewhat different product will develop. As an example, let’s look at the behaviour of carbon. Under certain temperature and pressure conditions, carbon burns and produces a gas called monoxide, or carbon dioxide. Under other conditions of temperature and pressure, carbon crystallises into the material known as graphite. Only under circumstances where there is a rare combination of extreme heat and high pressure does carbon crystallise into diamonds.
Our gem has formed! Now what does it take for it to grow? The growth process of crystals is similar to the attraction between a magnet and iron objects. Due to their electrical charges, the atoms of certain elements are attracted to each other. Once these atoms amass, they attract other atoms in the environment that then deposit themselves layer after layer on the growing crystal, imitating the order of the first atoms from which the crystal originated and forming the crystal structure.
A crystal continues its growth as long as it is able to attract new atoms from the surrounding environment without encountering any obstacles that hinder its development. This happens rarely in nature. In most cases, environmental conditions change before a gem-producing crystal has time to finish growing completely. Even when conditions remain stable, the neighbouring environment or competition with another crystal could mean that the growing crystal does not have sufficient space to reach its completion.