Agree with the above. In addition, the “RSG” part of the mark is an indication that this was a mass-produced pre-assembled setting, ready for a jewellery wholesaler or retailer to insert their own choice of stones according to intended style and selling price. The letters are trade shorthand for “Ready-Set-Go”. Typically these kinds of items are purchased in bulk and converted to finished jewellery for sale in chain stores and such, so they won't include anything beyond semi-precious stones, synthetic imitations or glass.