Wash the grapes well in cold water.

Pick the Grapes off their stems.

Squeeze them out of their skins into a stainless steel pot. Its totally fine if  a little skin stays stuck to the pulp.

Its a cumbersome process indeed but it doesn't take as long as you might think. The book suggested something on the lines of 15 minutes. For me, inspite of distractions galore from a little one trying to whisk the grape from the table to trying to capture photos, it took only 30 minutes.

Set aside the Grape skins. You will be using them later.

Yay! Pink fingers! Well you might have colored fingers even after washing them and you will be fated to remain with pink palms for the rest of your life..err..ahem! OK! Bad joke I know!

Place this pot of grape pulp over medium heat.

Cover and bring to a gentle boil.

Cook for about 5 minutes, stirring occasionally.

When the grapes have broken down to a mush remove them from the heat.

Place a large bowl in the sink and set the sieve over it. Pour the grape pulp into the sieve

and using a wooden spoon, push down the pulp through the mesh.

Discard the seeds.

Add the grape skin to the pulp

and bring it to a boil, stirring occasionally. Boil for 2 minutes wherein you will notice that the now this mixture has turned dark thanks to the color of the grape skins.

Alternatively while the jam was coming to a boil, warm the sugar in an 150F oven.

Gradually add the warm sugar, stirring in 1 cup at a time to the pulp.

Bring back to a rolling boil and cook stirring constantly.  Did you look at that color? Deep purple! Looks mindbogglingly good, isnt it?

How to check if your Jam is done?

1. Temperature Test – If the temperature (using a candy thermometer) shows 220ºF (or 104ºC), then the Jam is done. Make sure that your thermometer is placed vertically and the bulb is covered with the jam. The bulb should NOT touch the bottom of the pan.
2. Spoon Test – This is similar to how you test a sugar thread consistency.  Take a cool metal spoon and dip it into the boiling Jam mixture. When you life the spoon, if the Jam runs off the spoon like a syrup, then the Jam needs more cooking time. But if it is heavier and drops like slate/sheet off the spoon instead of flowing as drops, you know that the Jam is done.
3. Refrigerator Test - I mostly use this method to check the doneness of my jams. I keep a plate in the freezer and remove it when I want to test. I then pour a small amount of the boiling jelly/jam on this plate and let it sit in the fridge for few seconds. If the mixture gels /mounds and wrinkles when you push it with your finger, it's done. If runny and it does not have a body to it, then continue to cook the jam for few more minutes until it clears the nudge test.
More info in the Apricot Vanilla Jam Recipe