Argh. Black ceramic sink & limescale

[Notonthestairs]

We live in a hardwater area and our landlord has installed a black ceramic sink. It looked lovely once but now has a grey film of limescale over some areas.
I'm very nervous of damaging it.
I've tried vinegar/water solution and bicarb/water solution but they are still bits that are coated in limecale.
Any ideas as to what I can use? We are moving out in six weeks and I am desperate to get our deposit back!

If you live in a hard water area I fail to see how limescale deposits on a black sink are you fault. Use neat vinegar or lemon juice. Bicarb won't work because it's alkali - you need acid to deal with limescale.

Full fat coke

Yep, neat vinegar. Just be careful of the taps.

Viakal has done a lovely job on my (white) sink, don't see why it being black would make a difference?

Barkeeper's friend here