Before buying colored gemstones you must make yourself informed about gemstone terminology so as to make sure that the piece you are buying is of high grade. Gemstone clarity determines how perfect a particular gemstone can be. There are technical and non-technical terms used to describe gemstone clarity. Technical terms are VVS (minute to detectable inclusion), VS (minor inclusion), and SI (noticeable, obvious, prominent etc).

However to describe clarity gemstone sellers also use simple terms like clean, eye-clean and included along with the technical terms to make it easier for purchasers. Clean means there are no inclusions even under magnification and eye-clean means the gemstone has inclusions but is not visible to the naked eye.

If you are buying gemstones like amethyst, citrine, topaz, zircon etc which belong to the quartz family you can be sure of the clarity or perfection of these gemstones.
These are type 1 gemstones and the clarity of these stones falls mostly under VVS, VS etc. Then there are type 2 gemstones like garnet, ruby, sapphire etc which do have inclusions but are classified as minor, noticeable, obvious, prominent, affecting appearance etc.

There are also type 3 gemstones like emerald, red tourmaline etc and these always comes with inclusions. Gemstone clarity for such stones is described as noticeable, obvious, prominent, more prominent, affecting appearance/durability etc.

The above facts would help you when buying gemstones for yourself. You would know that a minute inclusion means imperfections that are not visible to the naked eye but only under 10x magnification. On the other hand you would understand that some gemstones have lot of inclusions naturally but these inclusions do not undermine the quality of such gemstones like for example a VS type3 gemstone has inclusions visible to the naked eye but still sells.