It has nothing to do with the gold coating it's just the easiest and most obvious way to distinguish them. I and even CPTBadAss can confirm they're just a slight bit heavier.
They're also longer/taller too.
I'd like to see a scale to scale comparison of both (for weight). I only have 62 gold springs in my boards now..
And from asking the kbdmod group buy runner, they are in fact the same spring (gold on an alloy of zinc, silver, and copper). So unless you got some jeweler to custom make real 24 karat springs, your "feeling" is placebo.
The gold you see on the spring is one cell thick, which is why it's affordable to do without actually raising the price by much.
The stiffness you talk about is probably because your springs have been broken in, as every spring decompresses over time albeit at a small rate.
I don''t get what the gold spring hype is about, other than the color of it (which is why I have it) but it's misleading to the public to sell them as a "superior" spring.
On the other hand copper springs are the best
although mine are like 60g... I ionized the stock (55g) steel springs in Cu(2) solution. in that case, the stiffness is because copper ions are more dense.