There is not a universal or standard table for grading the quality of emeralds. Most grading is done based upon these four facts: Carat weight or size of the gemstone. - Color: hue, brilliance, tone and saturation. - Clarity: visibility of inclusions and flaws. - Cut: how well the stone is cut.
You will see many different terms describing color and quality on many different websites such as: AAA quality, signature quality, top green quality, rich grass green, etc. Also, I've seen people offering "truly top high-quality emerald" at around $600.00 per carat, which it is not a realistic price or it is a wrong description.

I know all our customers want to know the real prices for emeralds in the market and especially for the quality of the emerald you want to buy; but "The value for emeralds depends upon who the seller is and who the buyer is"; where are you buying the emerald (direct seller or intermediary) and how wide is the selection to choose from (in stock or by ordering from another seller), intermediaries and international emerald traders increase two or three times the prices to the public because everyone wants profit.
We have a wide selection of loose emeralds in stock acquired directly from the miners and cutters in Colombia; my 30 years of experience and knowledge in the emeralds and jewelry business makes to me an expert and a smart wholesale buyer, to get the best quality emeralds available in town at the best price possible. We have listed only a few items, let us know what you are looking for.

It is not possible to create an accurate and understandable color and quality grading chart for all emeralds because the variety is really wide, so we narrow them to the quality emeralds that we handle:
From: good brightness, very good brightness to really good brightness and vibrant brightness. From light green to deep green, not black spots and not external fractures refilled with synthetic resins.
All genuine emeralds have natural flaws, from clean to naked eye to visible natural flaws; any emerald without inclusions is probably synthetic or imitation, because "emerald naturally are always included."
When the over saturated chromium and also sometimes vanadium atoms stress the emerald crystals, it produces internal micro-fissures what is called Jardin (flaws) "a unique garden of inclusions that gives to each emerald its one of a kind birthmarks." we do not acquire heavy included emeralds.

In my opinion the treatment for these internal micro-cracks is better to use a stable or permanent resin filling to prevent future changes within the gemstone once in the hands of the user, BUT NOT if it is to hide holes or serious external fractures that compromise the integrity of the gem, which is deceptive; In addition, the so-called commercial cedar oil used in laboratories for precious stone treatments is also synthetic.