I use the following system......I have a good microscope which can give a good picture of the stylus tip , 200x magnification and two powerful side lights at 90 degrees to the tube. I have a library of images of the 'cats eyes' to look for on styli types. I am a 50 year plus research biochemist with many years of teaching behind me so good microscopy is no problems for me. The stylus is mounted on a microscope slide with blue tack with the tip pointing up to the bottom objective lens. I use a click counter to count how many sides I play. I use a very good record cleaning regime ...not sonics but I believe it gives an excellent result. I check my new stylus when it comes out of the box. Then use it, I clean too with record cleaning brush and use a dust bug. I also clean my stylus every side with a brush. At 0, 500, 700 800 and then every 50 sides or so I put the stylus under the microscope. I check the "cats eyes" you see. If they are close to meeting then your stylus is at the end. I find I can get around 700hours on an elliptical, around 1000 hours on a fine line and maybe 500 on a conical. As I posted a black diamond seems to wear slower than a coloured or white diamond....
