Tea implements which are used in the tea room for practical purposes, have special features, firstly of shape and size (nari, koro). Rikyu also said that if the shape and feel are good then it can be called a tea utensil. There are also many special kinds of colours for chanoyu utensils. Looking at the shape and size of tea utensils in the tea room, firstly one sees that they are based on Rikyu's design and that the size corresponds to the size of the tatami in the tea room. This Rikyu gonomi (or Rikyugata) size is used by craftsmen everywhere when they make utensils, demands for the tea room being the same now as long ago.
Also the colour, which depends on the form and size of the utensil, is basically black, as in Rikyu's favoured utensils.
In Rikyu's words, recorded in the 'Sotan Nikki' diary by Kamiya Sotan when he was invited to Rikyu's tea gathering, 'Kuroki wa furuki kokoro' (black is the spirit of old), whereas, 'red shows a course spirit'. We can see how much Rikyu liked black, as opposed to red.
Of course not all tea utensils are plain black, but chanoyu utensils avoid the showy, and choose the refined simplicity, tranquility and clarity of black as the basic colour.
Chanoyu utensils also have a poetic name (mei). Giving names to the flower container, tea bowl and tea scoop makes the atmosphere of the tea room, in which a bowl of tea is drunk, and the pleasure experienced by the tea devotee, all the richer.
The name can come from the name of the owner, the place where the utensil is kept, the shape or colour of the utensil, the beautiful scenery of the four seasons, the various events of the year, from ceremonies of congratulations or condolences, as well as from precepts and teachings and so on. When utensils with names are put together in the tea room, there is unexpected and unusual enjoyment to be had from the names' associations. In this we can see how effective names are.