What should the powder and reconstituted solution look like?

Visual inspection is a quick first check, but it has limits. Lyophilized peptide is usually a white powder or a small, sometimes wispy "cake"; unusual color or an oddly sized cake can warrant questions. Once reconstituted with the appropriate diluent, the solution should generally be clear — cloudiness, persistent particulates, or material that won't dissolve can indicate a problem (though cloudiness can also come from a sub-spec or wrong diluent, not only the peptide). Slow dissolving or an under-filled vial are also worth noting. Important caveat: appearance cannot confirm identity, purity, or sterility — only laboratory testing (HPLC, MS, LAL) can. Treat looks as a screening step, not a verdict, and as research-material handling, not preparation for use.