Angle grinder - I use this blade for shaped cuts in tiles. Good results with patience
Abracs Tile & Porcelain Diamond Blade
10mm Segment height. For ceramic and porcelain tile cutting. Clean cut. For wet or dry cutting.Expert quality blade designed with X-Tech Cutting technology for porcelain cutting as well as a range of tile and ceramic cutting applications. The continuous X-Tech rim blade offers a combination of...www.toolstation.com
Might be able to undercut the riser so the tile goes under it.