1. *Good to Fine condition*: In a good to fine condition, meaning it shows moderate signs of wear and tear, a 1855 US 2 and half cent piece can be valued around $10 to $20.
2. *Very Fine to Extremely Fine condition*: A 1855 US 2 and half cent piece in very fine to extremely fine condition, exhibiting minimal wear, can be worth anywhere from $20 to $50 or more.
3. *Uncirculated condition*: An uncirculated 1855 US 2 and half cent piece, which means it was never put into circulation and remains in its original mint condition, can hold a significantly higher value. Depending on its specific grade, an uncirculated coin could be worth several hundred dollars or even more.
4. *Rarity and Special Varieties*: Certain varieties or sub-types of the 1855 US 2 and half cent piece may carry additional numismatic value. For instance, if the coin has specific die flaws or minting errors, it can increase its rarity and value among collectors.
5. *Market Factors*: The overall market conditions and demand for US coinage can also impact the value of a 1855 US 2 and half cent piece. Factors like changes in market trends, economic conditions, and buying preferences can influence the prices of such coins.
It's important to note that the actual value of a particular 1855 US 2 and half cent piece may vary depending on the specific circumstances and market conditions. Consult with reputable coin dealers, numismatists, or experts in the field to obtain a more accurate appraisal of the coin's worth.