long term gsecs have given remarkable returns this year. From Jan 2024 to Sept 2024, all gsecs having 15 or15+ years maturity have given more than 10% returns in 9 months. I had purchased 73GS2053 which has given 12% in 9 months.
When yields come down (which has happened over the last few months), price of the bonds go up. So the 7.54 coupon is only one part of the returns that these gsec investments are enjoying. The other component is coming from the appreciation in the bond prices. The cumulative effect is the 12% returns you’re seeing.