Scratches on Sapphire crystal

[Drulee]

I just screwed up my sapphire crystal. I have a few of those nice thick DSN Sapphires, which unfortunately have the light blue AR as well. So tonight I decided to remove it using those Diamond paste syringes.

Being the idiot I am, I completely overlooked the fact that Diamonds are harder than Sapphires, especially synthetic Sapphires.

Everything was going great, and quickly, as I started with 14 micron and worked my way down to 0.5 micron paste in about 4 steps. The whole process took about half an hour, using just the tip of my finger to rub the past over the back of the Sapphire. Most of the AR had been removed after the first 14 micron rubdown, but some remained around the outer edges.

Well after I had finished and washed the crystal down with some soapy water, I had a close look at the crystal surfaces under a loupe at different angles under a bright light only to find many hairline scratches all over the surface

Any thoughts on a good way to remove them? I read somewhere about using polishing rouge, but isn't that abrasive as well?

[redwatch]

Watchbitz sells a great sapphire polishing set of pastes that I have used with great success.

[PeteM]

Just to be clear are you saying you used the diamond polishing paste to remove AR???

I know how careful you are but are you sure these are scratches on the glass and not whats left of the AR which has not been removed? I have been tricked by this before. Also I are you saying if it is scratches its on the sandwich sapphire or full sapphire. I ask because it can make a difference using rouge.

[szvwj]

It sounds like you used the 14 micron, but did you go through the entire process and work your way down to the 1/2 micron paste?

From what I've read, the 1/2 micron shouldn't leave hairline scratches (but requires a lot of work). I am about to order some from McMaster carr (I have a screwed up BCE crystal).

[Drulee]

Yup all AR was removed. I started with 14 micron for a few minutes. Then I stepped down .. 2.5 micron one session, 1.5 the next, and finally 0.5 micron (reddish). The majority of the AR, basically all except around the edge, was gone after the 14 micron session. It took a few sessions with the 2.5 to get rid of it all.

Unfortunately I didn't put it directly under a lamp with a loupe until after the half hour session. I've been doing a few 2-3 minute sessions with the 0.5 and a cloth (used my finger tip in the beginning ), but there still seem to be a lot of very fine scratches. They actually aren't noticeable until I place the sapphire directly under the light bulb (2 inches away) at certain angles, and look very closely.

When I have time I'll do a few more sessions with the 0.5 micron paste.

Oh, and I've been using warm water with mild soap in it to wash the Sapphire between paste sessions

[praetor]

hmm, I think I see the problem. It's simple really, you can't dissolve diamonds in any solution. For the diamond paste, they are suspended in oil. So while washing it with soap might remove the oil, the diamonds are still there to scratch.

[maxman]

I used a cape cod on my SA when ss polish did not remove all the ar. the cc worked beautifuly. No scratches can be seen,not even under a loup

[PeteM]

I think given what you have said you are just going to have to go through the finer process again, it is very time consuming and may never be perfect in your eyes certainly

Next time and without wanting to sound patronizing I suggest you use other methods to remove the AR as thats quite a pricey and time consuming method to use.

The best is always the medium felt wheel on a dremel and rouge. Though if its on a dome crystal only use a smaller dimensioned wheel as the bigger wheels create more heat more quickly.

I read recently about a member hat uses CC to thin out rep AR with gently motion and wax ear buds!! the results seem good in pics though close up remains to be seen..I need to try myself when the opportunity arises

If you dont have a dremel then I have never needed anything more than SS polish and Micro fibre small grade to remove AR, including Chiefs coating or any of the harder coatings.

Good luck mate

[Rolexman]

Cape Cod is the safest way to remove AR. You don't need heavy compunds as AR isn't that tough.

[Drulee]

Cape Cod is the safest way to remove AR. You don't need heavy compunds as AR isn't that tough.

Unfortunately, I had read quite a few posts saying that CapeCod would not do the trick .. should have just tried it anyway

When I get a few spare minutes I've been going over it with 2.5micron, then 1micron, and finally 0.5micron. It seems to be slowly getting there .... will probably just stick to 1 and 0.5 micron, then finish it off with a buffing wheel and some rouge ..

[praetor]

I've successfully stripped AR with normal paper/sandpaper and Mother's Aluminum Polish in 5 min. The only reason why anyone would need to use diamond paste is to remove scratches or reshape the crystal, but in your case, it caused scratches LOL. Lesson learned =)