To'ak Chocolate is offering a $260 bar of chocolate — and the candy maker points to genetics to justify the steep price.

The company say the chocolate is sourced from cacao trees that represent one of the last genetically pure remnants of a rare heirloom variety called Nacional.

Native to Ecuador and famous for its complex flavor profile, Nacional cacao was considered by many of Europe's earliest chocolatiers to be the world's most prized cacao in the 1800s.

The variety was nearly driven to extinction in 1917 after the outbreak of Witch's Broom disease, and in recent years many experts did not believe that pure Nacional cacao trees still existed.

However, To'ak co-founders Jerry Toth and Carl Schweizer found a grove of Nacional cacao trees growing semi-wild in the valley of Piedra de Plata, deep in the hills of coastal Ecuador. The trees were planted at the turn of the century.

Toth and Schweizer brought leaf samples from the trees to research geneticists Dapeng Zhang and Lyndel Meinhardt at the USDA's Sustainable Perennial Crops Laboratory in Maryland.

Genetic analysis by Zhang and Meinhardt confirmed the existence of the pure Nacional genotype among these samples.

Dr. Zhang writes, "Our hypothesis is that these trees represent the original Nacional cacao cultivated in Ecuador before the 1920s. After that, most of the trees were destroyed by the [Witch's Broom] disease, and the original variety was replaced by hybrids, which are more disease-resistant."

To'ak Chocolate was born from a rainforest conservation project in Ecuador. In 2007, Toth co-founded Third Millennium Alliance, a rainforest conservation foundation that currently manages a 1,000-acre forest preserve in Ecuador.

Now, Toth and Schweizer are working with cacao growers in Piedra de Plata to protect these rare Nacional cacao trees and sustain the genetic line through grafting and seed banks.

Those interested in trying one of the $260 bar better hurry though. To'ak produced only 574 bars of its inaugural edition, and only 115 bars are still available. Each bar is packaged in a hand-crafted Spanish Elm wooden box that has the individual bar number engraved on the back. The box includes Spanish Elm tasting utensils and a 116-page booklet that provides a guide to the ritual of dark chocolate tasting and tells the story of the rare bean's sourcing. The bars are available on the To’ak website  and at select retail locations.