Rosewood is generally more expensive than black walnut. This is due to several factors, including rarity, demand, and the legal restrictions surrounding its trade. Rosewood is a term that encompasses several species of trees, all of which are highly prized for their rich color, density, and workability. The most sought-after species, such as Brazilian rosewood (Dalbergia nigra) and Madagascar rosewood (Dalbergia baronii), are subject to international trade bans and restrictions due to overharvesting and habitat destruction. These legal restrictions have driven up the price of rosewood, making it one of the most expensive woods in the world.

On the other hand, black walnut (Juglans nigra) is a more common species, widely available in North America. While it is still a premium wood, its price is significantly lower than that of rosewood. Black walnut is valued for its rich grain patterns and durability, making it a popular choice for furniture, cabinetry, and flooring. However, the demand for rosewood, especially in the luxury furniture and musical instrument markets, has created a higher price point.

According to the Wood Database, the price of rosewood can range from $20 to $100 per board foot, depending on the species and quality. In contrast, black walnut typically costs between $3 and $10 per board foot. These figures highlight the significant price difference between the two woods.

The rarity and legal status of rosewood contribute to its higher price. For instance, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) regulates the trade of rosewood species, which has led to a scarcity of the wood in the market. The demand for rosewood in the luxury goods market, particularly in Asia, has further exacerbated this scarcity.

In conclusion, rosewood is more expensive than black walnut due to its rarity, legal restrictions, and high demand. The price difference is a reflection of the wood's unique properties and the challenges associated with its sustainable trade.