I have just bought a white Rosenthal laughing rabbit with a red mouth, pale pink eyes and pale pink ears. Marked Rosenthal, Bavaria, Germany. Marked 510
And your question is?
The design was created by Max Fritz in the 1930s and your mark sounds like a version used after 1947 but that means nothing as it can still be purchased from Rosenthal today, e.g. the pure white 'Rosenthal Classic' edition normally costs EUR 29.95 (USD 41.50, Rosenthal store price) but is frequently seen offered for prices around EUR 17.90 (USD 25, Rosenthal online special offer).