Chocolate's glossy dark exterior and shell-like toughness, comes from tempering. During tempering, seed crystals form in the chocolate allowing it to harden into a brittle state when cooled. Tempering chocolate is a confectionery method that has been used for decades. It requires a large marble slab, which is not a common feature in many homes. The seed method of tempering, however, requires nothing but a bowl, chocolate and a spoon.
Melt your chocolate using any method that works best for you; the double boiler method is the most universal and tends to yield the best results. Place a double-boiler fitted pan, small saucepan, or glass bowl above a slightly larger pan of simmering water. Keep the pan simmering over low heat while you melt the chocolate. Stir constantly to ensure an even temperature until completely homogeneous.
Transfer the melted chocolate into a room temperature glass bowl. Quickly add two to three chunks (about 2 oz. size) of solid block chocolate per pound of melted chocolate and stir it briskly with a spoon. This seeds the chocolate while cooling it down.
Allow the chocolate to cool to its tempering temperature: 88 to 90 degrees F (31 to 32 degrees C) for dark or semisweet chocolate, 86 to 88 degrees F (30 to 31 degrees C) for milk and 80 to 82 degrees F (27 to 28 degrees C) for white. Keep the chocolate at this temperature until you are ready to use it. When it dries, it will be brittle and shiny with a distinct cracking noise when broken.
Melt the chocolate as outlined in Step 1 in the above section.
Pour one-third to two-thirds of the liquid chocolate onto a large cool marble counter (at least 16-by-16 inches). Keep the remaining chocolate in the pot warm.
Spread the chocolate with large dough scrapers (or flat paddles, large-scale icing knives or spatulas work well) and allow it to cool for up to a minute. Hold your hand over the top, if you no longer feel heat rising then it is ready to temper.
Fold the chocolate over onto itself using the scrapers. Literally use the scrapers to puck up and move the chocolate onto itself. Do not scrap the hard solid pieces closest to the counter or there will be clumps.
Continue to fold until the chocolate begins to thicken like a batter. When it reaches cake batter consistency the seeding is complete.