Is it possible to grow an avocado from its stone?

Yes, it is possible, but you better try several avocado pits.
STEP 1 – REMOVE & CLEAN PIT

Rrmove the pit from the avocado carefully (without cutting it), and then wash it clean of all the avocado fruit (often it helps to soak the pit in some water for a few minutes). Be careful not to remove the brown skin on the pit – that is the seed cover.

STEP 2 – LOCATE WHICH END IS ‘UP’ AND WHICH IS ‘DOWN’

All avocado pits have a ‘bottom’ (from where the roots will grow), and a ‘top’ (from which the sprout will grow). The slightly pointier end is the top, and the flat end is the bottom. In order to get your pit to sprout, you will need to place the bottom root end in water, so it’s very important to figure out which end is the ‘top’ and which is the ‘bottom’.

STEP 3 – PIERCE WITH FOUR TOOTHPICKS

Take four toothpicks and stick them at a slight downward angle into the avocado seed, spaced evenly around the circumference of the avocado. It is better to stick them in at a slight angle (pointing down), so that more of your avocado base rests in the water.

STEP 4 – PLACE AVOCADO SEED HALF SUBMERGED IN A GLASS OF WATER

And set on a quiet windowsill with sunlight. It is better to change the water every five days to a week or so. Prevent mold, bacteria and fungus growth with changing water regularly.

STEP 5 – WAIT FOR YOUR AVOCADO SEED TO SPROUT!

Sprouting can take anywhere from 2 to 8 weeks.

1. The top of the avocado pit will dry out and form a crack, and the outer brown seed skin will slough off.

2. The crack will extend all the way to the bottom of the avocado pit, and through the crack at the bottom, a tiny taproot will begin to emerge.

STEP 6 – POT IN SOIL WHEN TREE IS TALL ENOUGH

When the stem is 6-7 inches long, cut it back to about 3 inches, this will encourage new growth. When it hits 6-7 inches again, pot it up in a rich humus soil in an 8-10″ diameter pot, leaving the top half of the seed exposed. Place on a sunny windowsill. Avocados love sun – the more sun the better.

STEP 7 – WATER & WATCH IT GROW

Give it frequent waterings with an occasional deep soak. The soil should always be moist, but not saturated. Yellowing leaves are a sign of over-watering; let the plant dry out for a few days.

STEP 8 – PINCH OUT TOP LEAVES TO ENCOURAGE BUSHINESS

When the stem reaches 12 inches tall, pinch out the top two sets of leaves. This will encourage the plant to grow side shoots and more leaves, making it bushy. Each time the plant grows another 6 inches pinch out the 2 newest sets of leaves on top. Good source