Anyone have Corian in the bathroom or kitchen

I have Corian worktops in the kitchen, fitted only 3 months ago so I can't vouch for their long term durability. I was warned by several people - including the kitchen supplier ^ that a Corian sink would stain badly so the sink is stainless steel.
So far, it has lived up to my expectations; it's solid and beautifully made, easy to keep clean with a damp cloth and anti-bac spray and it looks great.

We have had dark grey Corian work surfaces throughout our busy kitchen and two bathrooms for the past 20 years, including a kitchen sink with Corian sides and a stainless steel base. It has shrugged off everything thrown at it, and looks just about as good as it did when first installed. I would unequivocally recommend it.

Hard wearing, but it can stain if spills aren’t dealt with quickly. A friend has it and I’m impressed that his worktop and sink appear seamless. He said it was expensive and it had to be installed professionally.

My daughter has had a new kitchen with white coriander worktop. Looks lovely but the sink has already gained an immovable stain!

What is it ?