Pupils are apparently 2-4 milimetres. As a middle I will be using 3 milimetres.
Dio's Eye: 9 pixels (0.003 metres)
Emerald: 170 pixels (0.056666666666666670737 metres)
Emerald: 25 pixels (0.056666666666666670737 metres)
Explosion: 478 pixels (1.0834666666666668 metres)
Radius: 0.5417333333333334 metres
W = 0.5417333333333334^3*((27136*1.37895+8649)^(1/2)/13568-93/13568)^2 = 0.00001277739121 Tons of TNT or 53.46060482264000058 Kilojoules.
Wall level
Apparently a leg makes up 44% of the human body. Edit: It was suggested as well to only measure the horizontal line.
Dio's leg: 442 pixels (0.8140000000000001 metres)
Emerald: 76 pixels (0.13996380090497737 metres)
Emerald: 25 pixels (0.13996380090497737 metres)
Explosion: 478 pixels (2.6761078733031676 metres)
Radius: 1.3380539366515838 metres
1.3380539366515838^3x((27136x1.37895+8649)^(1/2)/13568-93/13568)^2 =0.00019253353092 Tons of TNT
Wall level