colour specification for gray colour

I have a line taken fron wavelet3d demo

hiso = patch(isosurface(Ds,5),'FaceColor','k','EdgeColor','none');

k gives black colour,but i need gray colour instead of black,please tell the colour code for gray colour

Answer 1

[Image Analyst]

Use a 1 by 3 array of numbers in the range 0-1, for example:

hiso = patch(isosurface(Ds,5),'FaceColor',[0.5 0.5 0.5],'EdgeColor','none');