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Color variations and sometimes the frosted appearance of Chinese blue-and-white porcelain produced in folk kilns and recovered in underwater archaeological contexts are usually reported without further investigation. This study focuses on the causes responsible for the appearance of the glaze and blue decorations of late fifteenth-century blue-and-white porcelain from the Santa Cruz, one of the most important mid-Ming shipwrecks discovered in Asian waters. Besides detailed visual observations, chemical composition and colorimetric data were collected on a set of similarly shaped plates showing significant differences in the aspect of the glaze and tones and shades of the blue color. Results from portable X-ray fluorescence (pXRF) analysis confirmed the Jingdezhen origin of the ware and the use of domestic asbolane ores for the Co-based blue pigment. Visual and microstructural analysis has shown that the degree of opacity of the glaze is primarily linked to the crystallization of anorthite, which in some cases has pushed the pigment layer towards the surface, contributing to the development of white-brownish weathering spots. The colorimetric data acquired with fiber optics reflectance spectroscopy (FORS) allowed us to quantify chromaticity parameters and confirm the visual perception of a ‘not-so-blue’ color of the decoration. Without excluding a possible contribution of the underwater environment, the observed variations can be mainly attributed to the ware’s production and more specifically to pigment characteristics, manufacturing processes, and firing conditions even though the connection with these factors is not straightforward and prompts further research and broader discussions. From a historical perspective, it is suggested that the atypical hues are correlated with the progressive switch from foreign to domestic pigment sources during the Chenghua period (1465–87 CE) and the subsequent technological adaptations required by an ever-increasing demand for Chinese blue-and-white porcelain at the turn of the sixteenth century.

The arrival of the Spanish naval expedition in the Philippines in 1521 CE transformed the archipelago from a series of small and fragmented ports and polities engaged in Southeast Asian intra-regional trade into a locus of a maritime trade network on a global scale. Manila became an entrepôt in the sixteenth and seventeenth centuries due to the Manila-Acapulco galleon trade, which ran for 250 years and linked the eastern and western worlds through the exchange of tangible trading commodities and technology as well as ideas, beliefs, and traditions. This chapter provides a brief historical background of the maritime trade in the Philippines, with special focus on the Manila galleon trade. It also provides a summary of the excavation results of Philippine underwater sites that have been dated to the sixteenth and seventeenth centuries. The shipwrecks include the Manila galleons San Diego, Nuestra Señora de la Vida, Encarnación, and San José as well as other shipwrecks: Española, Marinduque, Royal Captain Shoal, and San Isidro. These vessels carried both peoples of different nationalities and a wide range of trading and utilitarian goods, and they provided valuable information on the diversity and complexity of maritime trade in the Philippines at this time.