The unique and visu­ally mes­mer­iz­ing ap­pear­ance of pear­les­cent ma­ter­i­als has made them an in­dis­pens­able in­gredi­ent in a di­verse ar­ray of ap­plic­a­tions in­clud­ing pack­aging, ceram­ics, print­ing, and cos­met­ics. In con­trast to their nat­ur­al coun­ter­parts, such syn­thet­ic ex­amples of pear­les­cence are cre­ated by dis­pers­ing mi­cro­scop­ic in­ter­fer­ence pig­ments with­in a dielec­tric res­in. The res­ult­ing space of ma­ter­i­als com­prises an enorm­ous range of dif­fer­ent phe­nom­ena ran­ging from smooth lus­trous ap­pear­ance re­min­is­cent of pearl to highly dir­ec­tion­al metal­lic gloss, along with a gradu­al change in col­or that de­pends on the angle of ob­ser­va­tion and il­lu­min­a­tion. All of these prop­er­ties arise due to a com­plex op­tic­al pro­cess in­volving mul­tiple scat­ter­ing from plate­lets char­ac­ter­ized by wave-op­tic­al in­ter­fer­ence. This art­icle in­tro­duces a flex­ible mod­el for sim­u­lat­ing the op­tics of such pear­les­cent 3D mi­cro­struc­tures. Fol­low­ing a thor­ough re­view of the prop­er­ties of cur­rently used pig­ments and man­u­fac­tur­ing-re­lated ef­fects that in­flu­ence pear­les­cence, we pro­pose a new mod­el which ex­pands the range of ap­pear­ance that can be rep­res­en­ted, and closely re­pro­duces the be­ha­vi­or of meas­ured ma­ter­i­als, as we show in our com­par­is­ons. Us­ing our mod­el, we con­duct a sys­tem­at­ic study of the para­met­er space and its re­la­tion­ship to dif­fer­ent as­pects of pear­les­cent ap­pear­ance. We ob­serve that sev­er­al pre­vi­ously ig­nored para­met­ers have a sub­stan­tial im­pact on the ma­ter­i­al's op­tic­al be­ha­vi­or, in­clud­ing the multi-layered nature of mod­ern in­ter­fer­ence pig­ments, cor­rel­a­tions in the ori­ent­a­tion of pig­ment particles, and vari­ab­il­ity in their prop­er­ties (e.g.~thick­ness). The util­ity of a gen­er­al mod­el for pear­les­cence ex­tends far bey­ond com­puter graph­ics: in­verse and dif­fer­en­ti­able ap­proaches to ren­der­ing are in­creas­ingly used to dis­en­tangle the phys­ics of scat­ter­ing from real-world ob­ser­va­tions. Our ap­proach could in­form such re­con­struc­tions to en­able the pre­dict­ive design of tailored pear­les­cent ma­ter­i­als.