The cherries are whatever are in the shops at the moment. I would say they are the sweet cherries as you can eat them raw without wincing.
I bought a cherry stoner to help and it certainly makes getting the stones out very quick.
I will do a proper writeup for the recipe with pictures but since it takes 14 days and cherries are short season, here is the quick and dirty version...
Cherries (any type) - 450g
Water - 570ml
Sugar - 750g
Wash and pit 450g of cherries. Place in a medium saucepan with 570ml water. Heat to just before simmering for one minute. All you want to do is warm the water to soften the skins but not cook the fruit. Drain the cherries and reserve the liquid. Return 425ml of the liquid to the pan and dissolve 250g of sugar. Bring to a simmer to fully dissolve the sugar then pour the hot syrup over the cherries and leave 24h.
Day 2 - drain the cherries into a bowl and return the syrup to the pan. Add 60g sugar and simmer to dissolve. Pour hot syrup over cherries and leave 24h.
Day 3 - repeat Day 2.
Day 4 - repeat Day 2.
Day 5 - repeat Day 2.
Day 6 - repeat Day 2.
Day 7 - repeat Day 2.
Day 8 - Add 85g sugar to the syrup without draining the cherries. Bring the cherries and syrup to a low simmer to dissolve sugar, Simmer for 3 minutes then set aside for two days.
Day 10 - Add remaining 55g sugar, simmer cherries and syrup for 3 minutes then set aside for 4 days.
Day 14 - Drain the heavy syrup from the cherries and keep it to put over ice cream and cakes. Spread the cherries out on a tray in a warm, dry place for 48h or put in your dehydrator on 115F / 45C for 12h till slightly dried.
They will not be bright red and they will not be in the sticky syrup that the supermarkets have got us used to.