From my search, the Ruby revolver became the Ruby Extra in 1955 and continued in production until 1970. I think yours for .38 Long* instead of .38 Special is a Model 12 from early in that period; call it mid-1950s.
Production line engraving and plating do not add a whole lot of value.
In 1974 an engraved Llama** Deluxe was about the price of a blue Smith & Wesson. I doubt they sold many, there are sure a lot more plain blue S&Ws than there are engraved Llamas or Rubys out there.
*There was a Spanish 9mm Largo revolver cartridge that was very close to .38 Long Colt. Yours is likely marked .38 Long for sale in the Americas instead of the home market.
**Gabilondo guns were trademarked Llama for US sales instead of Ruby at that time.