Pure doesn't strictly have a glow per say, it's more like an HDR kinda thing where R, G, and B values go beyond 255. In game this appears as if the color gets shaded less. In turn, this allows you to actually have a wider range for color. If you want your pure joints to have the same color as your bodyparts, you should use slightly grey joint textures. From testing, #c4c4c4 looks pretty darn close

(applied to pecs, pure with a grey joint texture on the left, #ffffff on the right)