Mali Garnet dispersion range: 0.028 to 0.057 and Demantoid Garnet 0.057
I’d say dispersion is only one factor in assessing quality, so colour, cut, clarity matter more than dispersion, which, though helpful, will not define the stone as top grade on it’s own.
Yellow and orange Emeralds? Even yellowish and orangeish would be odd terminology for an Emerald in my opinion. Look here and check the shade of green nearest to the stone you’re considering (the options bar has a green rectangle outlined with red):
If it’s not there it’s not likely to be very commercial.
There is a possibility that you’re looking at another member of the Beryl group.
Oops! I just re-read this and realised you’re still talking about Mali garnet.
That is a bit easier to answer. As you move from green to brown the price drops so yellow is a slightly better option, but any shade of green is likely to be a more valuable if all other factors are equal.
Mali Garnet has a very big price variation per carat.
Sorry for the confusion
The dispersion in Mali Garnet has quite a range so if I had to choose between two otherwise equal stones, higher dispersion would the winner, but if one had higher dispersion but poor clarity or colour, I’d opt for the best colour and clarity. Colour beats cut and clarity is certainly as important as cut. There is a judgement to be made because in general dark colours hide some clarity issues better and so cut might have an edge. Light stones throw up another problem in that ‘windowing’ makes a stone with good clarity, look less appealing. Personal preference is the factor you can never allow for with any customer.
Demantoid will have good dispersion so the 4c’s make all the difference
While green may be the preferred color for mali garnets in general, I personally prefer yellow. Tsavorites and demantoids already fill the green slot for me, and the only yellows I have ever seen are the mali garnets.