Bottom line, men are just not good at buying shiny jewelry and gems. Its all these tiny little shiny objects, that leave you staggered at how something so small can cost so much. There's an actual physiological reaction where a man's body freezes up and his brain becomes mushier than normal at the mere mention of jewelry.
General consensus, in the literature as well as numerous comments here on this very blog, is that if you have a Meta gem that requires 2 Blue gems, you can have zero blue gem slots in your gear, and populate two red gem slots with purple gems, and satisfy the requirements of your Meta gem.
I tried this. A while ago.
The metagem still came up greyed out, as if to indicate the requirements were not satisfied.
My memory is fuzzy. Perhaps my test was flawed.
I will try this out again, and then I will slap myself silly for reaching into my gold stash so frivolously.