Combine the cream, mango, orange juice and zest in a blender and puree until smooth and liquid.
Melt the 40-percent and 70-percent chocolates over a double boiler. Bring the cream-fruit mixture to a boil, pour over the bowl of melted chocolate and emulsify using a rubber spatula. Finally, emulsify with an immersion blender to obtain a smooth ganache.
Line a 8 by 8-inch baking pan with parchment paper.
Once the ganache has cooled to room temperature (95 to 104 degrees F), emulsify the butter into the ganache and pour into the prepared baking pan. Allow to crystallize and firm up overnight. Then cut into 1 1/4-inch squares.
Temper the dark chocolate by melting it to 140 degrees F, then cool over a cold water bath to 86 to 90 degrees F. Pour the tempered chocolate into the cavities of the mold, then flip the mold over the bowl of chocolate and tap to let the excess chocolate fall back into the bowl. Scrape the top of the mold clean, leaving only the thin shell of chocolate in the cavity. Allow to crystallize at room temperature for 1 hour (you can put in the fridge for 10 minutes to expedite the process).
Dip the squares into the tempered chocolate using a fork, taking care to drip off all excess chocolate to obtain a thin shell. Before the chocolate hardens, garnish with the coconut.
Cook's Note: If you don't want to dip the chocolates, you can scoop and roll the balls in small-flaked unsweetened coconut to make chocolate truffles. This is much easier.