I read about Leif from Pricescope, an engagement ring forum. His reputation is pretty extensive as he comes recommended by Whiteflash as one of the top custom jewellery designers in Toronto.
So I took a trip down to the Distillery District and met him in person. Leif is very passionate about his work and he is very enthusiastic about collaborative design. My impression is that he specializes in gold metallurgy, intricate engraving and settings. Leif can also help to source stones for you if you did not already have one.
I got my engagement and wedding rings done here, both of which are custom and very unique. I have had compliments from family and friends, even strangers! So yes, he's highly recommended.