Featured 9ct gold metal cored bangle what is this mark?

It's marked 9ct gold metal cored 20 microns, R and then a heart shaped mark with letters F and M in it, not sure what the R and heart means? I'm hoping it might help me date it.

 

F and M made gold plated bangles....perhaps heavily gold plated?

 

20 microns is more like rolled gold I would think

Looks like a rolled gold mark anyway

 

R probably stands for rolled

 

Thank you!

 

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Metal-core Gold jewellery is similar to Gold cased and rolled Gold, but is far thicker and more durable. For instance a bangle may be called "9ct Gold Metal Core" meaning that a thick shell of 9ct Gold is bonded to either a jeweller's alloy or base metal.


https://www.etsy.com/listing/1398708216/vintage-9ct-gold-metal-core-20-microns-r

 

Thank you @komokwa I didn't find this one when searching, none of the others I found had the same mark and the date estimates were a bit far flung. My guess was 1960s and it seems this seller agrees.

 

yer welcome...!

Many hands make light work !!