The main difference between a natural and a lab-created sapphire is its origin. Both are created using identical materials and have the same molecular make-up. Lab-created (synthetic) sapphires have the same physical properties, visual characteristics and hardness level as the natural gemstones. Natural sapphires are created by the earth and mined, making them rare. The lab-created stones are created by man in a carefully controlled environment and are common.
Sapphires are made of corundum, also known as aluminum oxide. The heat used to make the stone comes from the earth and they are mined from the ground. The natural gemstones are valued for their rarity and the fact that no two are alike, making each one unique. Natural sapphires have natural inclusions (flaws) in them, and exhibit a distinctive colour based on the region they are produced from. Many choose a natural sapphire simply because of the mystery and romance associated with owning a "natural" stone.
Lab-created sapphires are made using corundum, just as the natural gemstone is. However, they are created in a laboratory and grown under carefully controlled conditions, simulating the high pressure and heat of the earth to replicate a natural sapphire. The heat used to create them comes from a machine and produced by either flame fusion or a flux-melt method. Lab-created sapphires do not scratch or chip more easily than the natural stones, and are valued for their AAA pure quality rating.
Natural sapphires have inclusions, which are flaws or "specks" as a result of gases and minerals being mixed into the molten mass, and trapped within the stone during crystallisation and before cooling. Natural sapphires come in many varieties, such as light blue, deep blue, violet, purple, pink, orange or yellow. A "fancy sapphire" is one that changes colour. The lab-created gemstones are produced to emulate the exact colour and clarity desired. Since most consumers desire the traditional blue sapphire, there are not as many varieties in colour. The lab-created stones are relatively flawless, and have all the ideal characteristics of a top-quality natural gemstone. Only a gemologist can tell the difference between a natural or lab-created sapphire.
Although gemstones without flaws generally demand a higher price, flawless lab-created sapphires are substantially less expensive than the natural gemstones because they are so easily made. Natural sapphires are more expensive because they are rare, difficult to mine and include a labour cost. Natural sapphires with no inclusions command the highest price. "Fancy sapphires" are less expensive than the traditional blue, even though they are rarest of all sapphires, because the demand for them is less.