Hardness in terms of wire temper is a strictly relative term. You
can get spring hard lead if you draw it down enough, but that's a
very different thing than spring hard steel.
With that said, my experience has been that half-hard 14K gold is
springier than hald hard sterling silver. That makes sense to me,
since the 14K gold is more heavily alloyed than sterling silver. No
clue about the 18K though, and I couldn't tell you HOW much springier
the 14K is.
Someone on the list will probably come up with exactly the figures
that you need, but if not - here's your plan B... Check the chart
that I have on my site for % wire area reduction and resulting wire
temper: http://www.spiderchain.com/other/faq.shtml#temper You can use
that to get a good idea of what temper you're giving your sterling
wire. Then ask a refiner what would be the equivalent working temper
for 14K and 18K. Use the chart to work backwards to your starting
It'll be a bunch of plodding math, but at least it's a option if
none of the Fine Orchid Folk have a magical answer.
-Spider (wire and chain lunatic)