Thread: Is this a coticule a belgian blue-coticule combo?

this looks to me like a combo coticule anyone want to confirm it for me?

The fotos are not as good as needed to observe if it is a natural combo
Yes it is a yellow coticule on one side but you have not fotographed the other side.
Rub the dark side with wet sandpaper and if the slury produced is red-blue in color this side is a belgian blue if the slury is white then it is a slate.

As Yannis says - the slurry will be a lovely blueberry colour. Note the flecks of dark red in the close up attached on the blue side of this combo. Get a hand lens out and have a look. I would say it is a combo for sure.

cheers
Stephen

Originally Posted by Yannis

The fotos are not as good as needed to observe if it is a natural combo
Yes it is a yellow coticule on one side but you have not fotographed the other side.
Rub the dark side with wet sandpaper and if the slury produced is red-blue in color this side is a belgian blue if the slury is white then it is a slate.

If it were slate, the yellow coticule would have been glued to it, with a distinct straight line between the stones. As the photos indicate a gradual transition between the two colors, it is natural combo stone.

I realize that because it is not glued together it is a combo of some sort. Just not sure if the other side is usable as a hone.

The pics I have are a bit bigger and I do see one fairly large red fleck in one of the photos so my fingers are crossed.

I'll do the wet sandpaper trick when I get the stone and lap it. Should be in the mail on it's way to me soon.

I'd say that's definitely a natural combo with a usable blue side.

The blue can come in quite a range of blues. (I have one that's almost black.) And the seam between the blue and yellow can be definite, wavy, or blurred and gradual like yours. But yes that's a natural combo alright.

That looks like it will be a good usable stone for you once you lap it clean. Don't take off any more than you have to on that yellow side since the yellow layer is quite thin to start with.

The thing I like about lapping vintage stones is: pencil grid schmencil grid! The grime when it's gone will tell you you're lapped. Then, I do usually do a pencil grid as added measure and when that's off, I've got a flat stone.

Chris L

Thanks for the tip! Wouldn't want too loose too many of those rhombodecahedronwhirlygigs.

And the answer is YES! Bluberry love came out of the dark side of me hone! She is a vintage combo coticule! bout 7 inches long. Sweeet!

So from what I hear th e belgian blue is rated at ~4000 grit and the yellow about ~8000-10000. Any good threads fo newbees starting on coticules?

The blue is really 4k+, some say as high as 6k.

There are many threads on using coticules. A quick search should turn up dozens.