Each area has its own qualities. India often uses knots per square inch. Turky and Iran use metric system, so a rug 9 x 9 per cm
equals pretty much your 24 x 24 per square inch. Chinese ue the therm lines. It tells how many knots are on the length of one ft (30,5 cm). A quality that is close to yours is 300 lines. They all describe just about the same knot density. In the early 1980 the finest rug of the world was a Turkish Hereke with 4.000.0000 knots per m² or 2580 kpsi. In the late 1990 this was topped by chinnese rugs with 6.250.000 knots per m² / 4030 kpsi and then 9.000.000 knots per m² / 5805 kpsi. Then in 1998 a rug was presented by Zhenping from China with 15.500.000 kpsi / 9999 kpsi. All mentioned rugs are unbelivable expensive and are made to show the skills of the producers. A wool rug is already fine if it has ca. 200 kpsi and more, a silk rug should have at least 400 kpsi.