My third set of pots, not planting 2 of a kind together, still Grey! Why? Why are my flowers still grey?

If you use the fl calculator it will give you your correct seed and pot combinations to get jewels in your garden

The number you need to use for your garden id is 5717

https://myarduinoprojects.com/flcalculator/

So for example you will need to plant the rosa praecocia in either a wooden bucket or an upturned mushroom to get a jewel plant :)

Apart from Peta's very good advice, the magical black and white pots do work for magpies. The tulipa you got is not gray but white. So plant a tulipa on the black one too and you will have a black one.

If you need a 3rd color you will have to use the link Peta gave you or figure out the pots you need yourself. Only the regular pots from the 1st tab of the shop work. Any other special, seasonal, hand-painted or magical pot (apart from the black and white) will not work.

Your flower in the black pot is not a Tulipa, so is grey.  You need Tulipa Praecocias in the black and white pots, not Rosas (as you have).