gold spring bars Vs gold plated spring bars

[timelord]

I noticed that all the solid gold Rolex models I have seen all have gold spring bars or what appears to be gold.

I understand the reason why the gold spring bars are mainly used is that the steel tips would be too hard on the soft gold and therefore gold is used to avoid cutting into the gold cavity as gold is soft.

Until recently, I never expected to find gold plated spring bars as I thought they were all solid gold.I believe gold plated would not serve any purpose other than for cosmetic appearance. My question is; would that small plate of gold really be effective to avoid a steel spring bar putting too much wear on the soft gold? How would one tell which is plated and which is solid apart from trying to scratch them?