The Reserve Bank of India (RBI) on Friday said it has so far issued sovereign gold bonds (SGBs) worth Rs 5,400 crore.According to the apex bank, it has issued eight tranches of SGBs till date. "Investors in these bonds have been provided with the option of holding them in physical or dematerialised form," the RBI said in a statement.The scheme for SGBs was launched in November 2015 as an alternative to purchasing the precious metal.SGBs are denominated in multiples of gram of gold with a minimum unit of 1 gram and maximum of 500 grams, which is also the maximum allowed per person per fiscal. They can also be held in demat form for ease of trading. The bonds are sold through banks, post offices, Stock Holding Corporation of India, as well as the National Stock Exchange and Bombay Stock Exchange.The applications for the first tranche of the scheme for 2017-18 was opened from April 24 to 28 and the bonds were issued on May 12.