Hi Joe,
I do fully understand your question.
What I can say about the MPX2300DT1 is that the gel coating is on the backside of the device where a little nose is:

Attached you can find the documentation for both the gel, opaque filler and molding compound. The pigment id Ferro 61-88450. It is mixed 4% with the Dow Corning 7-9600 gel.
BR, Tomas