Our mains swatches with "gradients" are all the same for any water-based mediums (pigment, watercolour, gouache, acrylic...) and they are for showing undertones (and colour in its complexity).
Dry mediums have a similar "gradient" swatch, now for coloured pencil (pastel pencil, water-soluble coloured pencil...) on Daler Rowney Simply Drawing 120g drawing paper, and pastels (soft, hard, oil, water-soluble...) on Fabriano Tiziano 160g.
Currently, we don't have "gradient" swatches for water-soluble mediums when wet, and oils.
Masstones are painted separately, in a smaller size, and used for measuring colour data, which are then used for all colour functions on our website. They are shown as a tiny swatch before the colour name in lists, almost as life-size on the colour page, as well as in the "Dot chart" view of a brand/range.
Some masstones are directly measured from painted charts, mostly for gouche, acrylics, and oil ranges. We usually avoid measuring watercolour masstones directly from painted charts, and only use our own samples and dot cards for painting masstones.
If you are intersted in how different brands are represented with swatches, and as a result, are able to be shown in colour-based search etc., look for notations on our "Art mediums" pages.
" all" means that we have masstones and measured colour data for the whole range, and the brand is fully represented in all colour-based listings (which require measured colour data).
".../..." shows how many colours have "gradient" swatches within the full range.
All the swatches with watercolor technique are painted on a 300g/m² Hahnemühle Aquarell-Karton. It's a natural white, mould made, cold pressed watercolor board.