Ingame:

Gamma = 21, Brughtness = 15

GEM settings:

use the TrueColor shader.

#define GaussStrength 0.00 //[0.00 to 1.00] Amount of blur effect blended into the final image.
#define SSOA 1 //[0 or 1] Applies SSOA like shadowing effect.
#define GSat 0.98 //[0.00 to 1.00] Adjust GEM-Saturation (standard 0.75).
#define GTBright 1.20 //[1.00 to 1.16] Adjust GEM-TextureBrightness (standard 1.36).
#define GCBright 0.83 //[0.00 to 2.00] Adjust GEM-Contrast (standard 0.99).