I think you'll be looking for a long time... The 2541 in jet (black) is very scarce, though one turned up on Ebay recently and sold for quite a bit. As far as I'm aware, black was not a regular production colour for the 2541 figure, though at least a couple are known of. It also would appear that only the early style was produced in black, though I suppose it's not beyond the realm of possibility that some black later figures were made, either to special order or as an experiment, though I've not seen a single example in all the years I've been collecting Jobling.
By opaline do you mean pearl (moonstone opal) or opalique? Again figures in either of these colours are very rare, though I have it on good authority that there's an opalique 2541 in a private collection. I've never come across any examples in pearl though, but it seems reasonable to think it might have been trialled along with jet in the early days of production.