Hi there, thanks for the question! The transition is seamless due to the nature of Milestone (the finish on the left). The bamboo flooring was laid first, and the Milestone was applied second; it's finished by hand, so the edge can be very precisely matched to the bamboo.

thanks so much for the reply :-) so this kind of thing would be very difficult to achieve with good-quality tile and grout, i suppose?

Yes, you wouldn't be able to achieve the same look with tile -- although you may be able to design something clean using those materials.