ERTE ''L'ESPRIT DU COGNAC'' COURVOISIER NO. 6: Bottle Approx. Sealed Romain 'Erte' de Tirtoff ''L'Espirit du Cognac'' #6 Courvoisier Collector Cognac bottle with legacy booklet 10'' h x 6.5'' w. Box Approx. 11.75'' h x 8.25'' l x 3.5'' w. The Russian-born French artist Romain de Tirtoff, also known as Erte (born in November 1892), designed the bottles of this limited edition. The visuals present the 7 steps of cognac making. The blends consist of rare Grande Champagne eau-de-vie, some of them are from the end of the 19th century, when Erte was born. The 8th bottle, Inedit, wasnt actually part of the original launch, as it was released in 1995. Erte set prices can range from $8000 to $20,000.