Beautiful things are desirable, rare things are scarce. everyone wants rare and beautiful things that is why they are expensive. When things are expensive people tend to take care of them, this is a good thing because if people don't take care of the rare and beautiful things in this world then we will soon have none left.
The look of a coral has a big impact. If a coral is ordered and it comes in coloured down, the seller has 2 options, sell as is for less $$$, or keep to colour up with the risk of loosing the entire piece.
A good example would be Aussie Strawberry Shortcake Acropora.
These are just google images:
It usually comes in looking like this or worse:

But can be coloured up to this or better:

The seller has every right IMO to charge more for the coloured up piece, the price they decide on for both is entirely up to them, with the buyer having 2 options. Pay less for coloured down, or spend more for the coloured up.
Hidden gems are usually cheap because the time and effort hasn't been put forth to bring out the full beauty.
Time is $$
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