Inorganic Natural, Synthetic, Simulated or what?

Natural inorganic gemstones are those that are created by geological processes and (usually) dug from the ground. They may or may not have been enhanced in some way - by dyeing, irradiation or heating for example - but the important consideration is that they have not been manufactured in any way. The complexities of the geochemical and geophysical processes that create gemstones means that larger stones are usually flawed in some way, even if such flaws are not visible to the naked eye or even under a loupe.

Synthetic inorganic gemstones are manufactured (man-made, lab-created, lab-grown etc.) but are chemically and optically identical to the natural form, and because the chemical processes can be controlled are usually flawless.

Simulated gemstones (known as simulants) look like the natural form but are chemically and/or optically different.

To complicate matters some natural gemstones can also be simulants, as can some synthetic gemstones.

So...

• A diamond dug from the ground is always a diamond
• A diamond created in the laboratory is a synthetic diamond, but it is still a diamond
• A white topaz dug from the ground is always a white topaz, but it looks like a diamond so it is also a diamond simulant
• A white topaz created in the laboratory is a synthetic white topaz, but it is still a white topaz - but because it looks like a diamond it is also a diamond simulant
• Cubic zirconia does not exist in nature so cannot be either natural or synthetic - clear cubic zirconia is always a diamond simulant

• A lab-created diamond must be made of carbon and have the same molecular structure as a natural diamond in order for the term 'diamond' to be accurate.
• A lab-created blue sapphire must be made of corundum with minute  amounts of iron and titanium, and have the same molecular structure as a natural blue sapphire in order for the term 'blue sapphire' to be accurate.
• A lab-created ruby must be made of corundum with minute  amounts of chromium, and have the same molecular structure as a natural ruby  in order for the term 'ruby' to be accurate.

If you are buying synthetic gemstones make sure that you know their chemical composition before you buy. Ask the seller if the information is not voluntarily given. Gems described on certain websites as 'Lab-created emerald'  have turned out to be spinel, cubic zirconium, corundum (in which case they should properly have been described as green sapphire) or even glass instead of being beryl coloured by chromium.