Anecdotal sources suggest that "R" could mean Rolled Gold. However, Rolled Gold (Gold Overlay / Rolled Gold Plate) is usually stamped as RG, OG, GO, or R.G.P.
But there is usually an indicator number to tell you how much gold was used. E.g. 1/40 18K RG, this means that an 18K layer has been fused to a base metal AND that 1/40 of the total weight of the piece is 18k gold.
Sometimes purity mark (e.g 14K) can be accompanied by a second mark called a 'maker’s mark' or a 'jeweler’s stamp'. These are custom stamps or engravings placed in jewelry by whomever manufactured it. Sometimes they are letters or initials, and sometimes they are ornate icons (like a heart or a bell, for example).
Gold is among the most loved precious metals in the world. It’s a wonderful ornament to wear as well as a great hedge against inflation and falling markets. Another significant attribute of gold is that it can be liquidated easily around the world.
Check out some tips for buying gold jewellery at Business-standard.com.