I also do alot of gem cutting and lapidary work, i work with cerium oxide almost daily.
Optical lens glass has seriously small tolerances, useing cerium oxide to buff out the scratch will distort the lens beyond those tolerances and render it useless.
Another response you got was to buy a non working lens off ebay, use the part off it you need to fix lens. Thats, in my opinion, is the only way to fix next to sending it to nikon.
But cerium oxide is a waste of time, money and effort. imo.
Good luck.

Its been over 2 yrs since i posted this question, i have been a bit preocupied with medical issues. But have been back out shooting for several months now and thought i would update what i finnally got as replacements.
Nikon D7200, D810. (D7100 for wife)
Tamron 150-600 G2, 24-70 G2, (18-400 for my wife).
Nikkor 50mm 1.8, 18-140, (70-300 yup wife)
Sigma 70-200
I think i did pretty good. The bodies where used from Adorama in EX condition
Tamrons all new,
Nikkors all new
And the Sigma a lucky ebay purchase.
I took my time and think i did pretty good, i did not get it all for the amount the insurance covered, but im thrilled with all of it. Except the nikkor 18-140, wish i hadnt bought that one and used that money plus some to maybe get a nikkor 70-200 vrII instead of the Sigma. Don't know what i was thinking there.

Can anyone point me in the right direction to update the firmware on an older Sigma 50-500mm lens for a Nikon D7100?

thanks in advance

Well used Nikon D3 for sale or trade, also have a Nikon F5 for sale.
The D3 has a shutter count of 73,000+ however the sensor and shutter assembly where replaced at 72,500.
Would trade for a Nikon D7200 or tamron 70-200 g2, or tamron 150-600 g2.
Or $1200.00 obo. For both cameras.
Will consider other offers for trade or trade with cash.
Thanks
Will post pics later.

Thanks GN hed only be 20 miles from, I'll contact him.

I got a great deal on the above bodies and lenses, they are in need of some service or repair. I'm m
we to Colorado, is there a reliable,,, cheap place. To have them inspected and cleaned??
Thanks. BTW, for sale too.
Thanks again
Rich..

I have not heard of this, I will definitely check it out. THANKS!!!

Our house was broken into, the only thing taken was my photography gear and some memorabilia (22 signed baseball's from the likes of, hank Aaron, George Brett, Reggie Jackson, Babe Ruth, etc.)
We where only gone for 2 hours. The people reaspondable where caught two weeks later, after they had gotton rid of everything. Talk about a sick feeling.
One reason for such a low insurance offer is the 300mm 2.8 Was a gift and I did not have the receipt. But I'm going back to the insurance company Monday, I have obtained a copy of the receipt from my mother who bought it, and put together a better more accurate replacement valuation.

Thank you Alan, I had not thought of that. I have not accepted the insurance companies offer yet, so I'm definitely going to do some more research and go back to them with some more reasonable numbers.

Home owners insurance will cover $5755.00 after deductible.

I am in the process of deciding what to replace my recently stolen gear with. Lost in the theft was, D7100, D7000, D5200, Tamron 70-200 2.8, sigma 150-500, nikkor 18-55, 55-300, 300mm 2.8, 80-400mm.
I loved the 7100, so thinking of the 7200 Or 500. But, cost may come into play so ff may not be a choice.
My main desire is wildlife, BIF, some landscape.
Thanks for any advice.
So,,, what suggestions can anyone offer if you where in my shoes?