1. Grade and condition: The overall grade and condition of the coin play a significant role in determining its value. Coins in higher grades, such as Mint State or Proof condition, are usually more valuable than well-circulated coins.
2. Rarity: The mintage of the 1904 Straits Settlements One Dollar coin was 2,000,000 pieces. While this mintage is not particularly low, the rarity of the coin can still affect its value. If a particular date or variety is scarce or rare, it can command a higher price.
3. Numismatic value: The numismatic value refers to the value that collectors place on a coin based on its historical significance, rarity, design, and other factors. Coins that have historical importance or unique design elements may be more valuable to collectors and can fetch a higher price.
Given these factors, the value of a 1904 Straits Settlements One Dollar coin can range from a few hundred US dollars to several thousand US dollars. To obtain a more accurate estimate of its value, it's recommended to consult with a reputable coin dealer or numismatic expert who can assess the specific condition and rarity of the coin.