Cool Coin Trick  Coin Warp
By Kind Permission From Franc Karpo
Effect: Magician displays three coins, (nickels) on the table. !One coin is picked up by the right hand and placed into the left hand. A second coin is picked up and placed in the left hand along with the first coin. The third coin is placed into the right pants pocket. The left hand is opened to show that the third has travelled by magic into the left hand, making a total of three coins ! The three coins are then dropped onto the table. 
This entire sequence is repeated again revealing the coin has again travelled back into the left hand. The three coins are dumped onto the table.

Now when the left hand is opened, instead of the coins travelling back into the hand, the coin transforms into one big coin, a half dollar. 

Preparation: To do this you need you need four
coins instead of three. Ahha, that's
the secret! You also need a larger coin for the transformation. I like
to use four quarters and a silver dollar. I've also used four nickels
and a half dollar.
Basically you want to have a definite difference in the size of the coins, so that the transformation will be more dramatic. After the spectator shuffles the deck, have him fan them in front of his face with the backs of the cards towards himself. Tell him to start fanning at the top of the deck and continue to the bottom. Meanwhile, you watch for the card that has the same value as the top card and the same suit as the card second from top Here's what you do before you start: ( I'll assume that you're going to use four nickels and a half dollar. ) Place the big coin into your right jacket pocket. The extra, (4th) nickel is hidden in the right hand. Just try to relax the hand and not grip the coin with too much force. The other three nickels are on the table.
Performance: Pick up one coin from the table with the right hand, ( don't let anyone see the hidden coin. ) Place this coin into the left hand. Say to audience, "One coin in my hand." ( As soon as the left hand has the coin  make sure to close that hand.) Grab another coin from the table. Place this coin into the left hand along with the first coin, but, at the same time secretly drop the hidden coin into the left hand as well, making a total of three coins. Say," Two coins in my hand." ( Make sure to close your left hand after the coins are in it.) The audience believes that you have two coins in your left hand. Pick up the last,
( apparently 3rd coin ) from the
table with your right hand and openly place it into your right pocket.
Say, "And a coin goes into my pocket." But that's not what really
happens! Here's what's really going on: you pretend to place the coin into your right pants pocket, but really come back out with it hidden in your right hand. Just let your hand relax naturally by your side. "Did you see it jump back?" As soon as you say this, open your left hand and dump three coins onto the table to show that the 3rd coin has magically jumped from your pocket and back to your hand! ( Everyone will be watching the three coins so the heat will be off the hidden coin it your right hand. ) Now repeat the sequence again. The right hand picks up a coin and places it into your left hand; make sure not to expose the hidden coin in your right hand. Pick up another coin with your right hand and drop in into the left hand at the same time secretly adding the hidden coin. (You now have three coins in your left hand, but the audience is only aware of two) Now this is where we change it up for the big finish. The right hand picks up the last coin from the table and places it into the right pants pocket as before, but this time you really do drop the coin into your pocket and grab the big coin, ( half dollar or silver dollar; depending on what you're using ) and bring your hand out of your pocket keeping the big coin hidden from the audience. (Relax your right hand by your side.)
Ok, here's the final sequence. You have three
coins on the table with the big coin
hidden in your right hand.) "This time we will do it backwards. One
coin in my hand." Pick up one of the coins from the table with your
right hand and apparently place it into the left hand. What you really do is switch the coins. The right hand drops the big coin into the left hand while holding back the small coin. This takes a little practice, but it's not hard as it sounds. The closing of the left hand around the coin will cover the fact that you've switched them. This is the most important part of this coin trick. If you can this move smoothly, the coin trick will amaze everyone! At this point the
closed left hand has the big coin
inside of it. ( The audience thinks it has a
smaller coin ) The right hand has a small coin secretly hidden in it.
(There are two coins left on the table.) "And these two will go
into my pocket." The right hand with its hidden coin picks up the final
coins (at the same time) from the table
and drops all three coins into the right pants pocket. Now you are
clean. The left hand has the big coin and the right hand is empty. Casually show that your right hand is indeed empty. At this point, look at your audience and ask, "How many coins are there now in my in my hand?" Some will answer, "Two" some others will say "three." You reply, "Only one  a big one!" As soon as you say "only one", open your hand to show the transformation and dump the big coin on the table! Every time I do this people grab for the big coin. They want to check it out and make sure it's for real. The beauty of this trick is that you're clean with nothing to hide. Congratulations, you've just performed a miracle! Have fun performing with your free coin magic trick.
Key Points 1. Whenever you have a coin hidden in your hand, try to relax. Slightly turn your body to the left so that the back of the right hand is facing the audience. Also never look at your hand when you have a coin hidden in it. Remember the audience will follow your eyes. 2. Practice the routine in the mirror. Any mistakes will be evident. Especially practice the switch with the big coin. Sometimes people will see a flash of the big coin. That's OK because they will think it's the smaller coin. Remember you're the only one who knows about the big coin! 3. When you have this coin magic trick well rehearsed, you can substitute and use other objects. I've used four grapes and a small lemon or tomato. I've also used four pebbles and a stone. Use your imagination. 