cleaning diamond discs/ what is this?

[phonograph guy3435]

I was in Maine over the summer, and I got a few diamond discs. 1 has a big brownish-gray splotch that has a lot of surface noise when it is played, but only on the spot. the other one is mostly brown with a few black grooves (everything but the black grooves have a lot of surface noise). I've tried using alcohol and cotton balls, but everytime it does nothing.

[CarlosV]

when a diamond disc is played with a steel needle, the groove is eaten away and its surface turns into an ugly brownish color. It looks like your record suffered such fate, and if so, it is not recoverable.

[phonograph guy3435]

thank you! is this very common on them? and if this was from when it was bought this would've been a very costly mistake as these cost almost 20 dollars in today's money.

[JerryVan]

thank you! is this very common on them? and if this was from when it was bought this would've been a very costly mistake as these cost almost 20 dollars in today's money.

Well, it's a bit costly today too. A good rule of thumb is, don't buy records that look like that.