I recommend a copy of
The Complete Metalsmith by Tim McCreight. It's a great resource for almost any question you might ever have about the metals used in jewelry. I can't count how many times I've looked up basic information in it. It has nearly every chart you can think of, from birthstones for months, saints, etc. to alloys for every color of gold, to every type of gauge chart, to geometrical formulas for volume and area and great home-made formulas for patinas on various metals.
I've misplaced my copy, or I'd give you the real answer right now. In the meantime, try searching for
14kt yellow gold alloy or
yellow gold alloys and see if that does the trick. Or maybe check on ganoksin.com. Sometimes it's hard to find what you're looking for there, but it is an excellent jeweler's resource.
I second the comments about "hypoallergenic" -- it isn't a legally defined term. Even in cosmetics, I believe it means that less that 50% of the people who use it, have a bad reaction to it.
"Nickel-free" metals works for the most common jewelry/metal allergy. But some people are allergic to other aspects as well.
Nearly everyone can wear
Niobium, because it is a very non-reactive metal. Niobium ear wires are available in a variety of colors (including pink, blue, purple and copper), but not many shapes.
Have a great weekend!
--Polly