Determining the age of an unsigned porcelain sculpture requires a combination of art historical knowledge, scientific analysis, and careful observation. Here are the key methods experts use:

1. Material Analysis: Examine the clay composition and glaze. Older porcelain often contains unique mineral signatures due to regional sourcing. Modern reproductions may use synthetic materials.

2. Stylistic Clues: Study the sculpture's design, motifs, and craftsmanship. Compare it to documented works from specific periods or dynasties. Details like brushstrokes or decorative patterns can reveal its era.

3. Kiln Marks & Techniques: Even without signatures, subtle kiln marks or firing techniques (e.g., wood-fired vs. electric kilns) can indicate age.

4. Patina & Wear: Authentic aging shows natural wear, such as crazing (fine glaze cracks) or soft edges. Beware of artificial distressing.

5. Scientific Testing: Methods like thermoluminescence (TL) dating measure accumulated radiation in clay, providing an approximate creation timeframe.

For accurate results, consult a certified appraiser or use laboratory testing. Combining these approaches helps uncover the true age of unsigned porcelain artworks.