There’s no set price for a sapphire ring as there are many factors which affect the cost, such as the size of the sapphire, the colour and quality (including if the stone is heat treated or unheated), the design of the ring (including if any other setting gemstones are used), the ring size, and the craftsmanship quality etc.
If we consider a classic style sapphire engagement ring with a halo of diamonds, and a lovely blue sapphire between 1-2 carats, the price could be roughly between SGD5,000 to 10,000.