Beads for channel alignment

I am looking for a set of 100nm beads that I can use for aligning different channels. I want to add these beads to my sample (as people do with EM) and image across the green (488 nm excitation), orange (561nm excitation) and far-red channels (642 nm excitation). As I want to add these beads to my sample, I would like them to have signal intensities similar to my sample. Most of my signals are single mRNA FISH signals - with about 25-50 fluorescent dyes (Atto488, Cy3, Cy5). As I couldn’t find any beads that I could use which don’t saturate my camera or have intensities in that range (I have tried tetraspeck beads), I was hoping some of you might know of something that could help me out. I do have the option of using the 405nm for excitation, if the emission in the 750nm+ range as all my filters are long pass in that range. I am thinking of using nanodiamonds (from sigma) though I have no idea about their signal intensities other than what they say in the website or in worst case scenario doing custom labelling to get signals that I need.

Thanks in advance.