Jam from vineyard peach

My acquaintance with the liqueur and the fruit of the red vineyard peach has led to this recipe recommendation:

Ingredients:
Vineyard peaches
Gelierzucker (1: 1)
Juice of half a lemon

Get 500 g of vineyard peach (from the weekly market)
water and core
puree (for example with the magic wand)
Add 500 g preserving sugar and the juice of half a lemon
and cook for at least 4 minutes
Transfer to hot rinsed glasses and close immediately
store cool

If the result appears pale in color, you can add 1/2 nectarine (for 500 g of vineyard peach).