GEMs (Growing-Equity Mortgages) Love Machine 16 years ago GEMs (Growing-Equity Mortgages) Mortgages wherein yearly increases in monthly installments are adjusted towards outstanding principal and this serves to reduce the remaining loan term. Recommended for you: Graduated-Payment Mortgages (GPMs) Growing-Equity Mortgage Negative Amortization Savings-Savy Borrowers Look to Credit Unions for 5-Year-Fixed Mortgages