The original coating on the fork legs is called "hard chrome" very very expensive to renew - as junaidakhter said - its due to dust settling into the little boots which then acts like emery to grind away the chrome layer.
If you can find a newer set for your bike then that is the most economical repair - otherwise you will be spending about Rs 5000/- or more for rechroming the fork legs like I did (but I am a bit crazy) Front fork oil is supposed to be changed out every year to keep them in good condition, because the oil inside them collects dust from the top and breaks down by being worked in the hydraulic chamber. If yours went hard I believe the oil being used was too thick or the regulating valve blocked up with debris, Your CG125 forks use 10W30 engine oil, the older ones with external springs used ATF
