In our injection molding facility, we have to pay attention to the color of the product coming out. The only method we have to verify the color is comparison to a color chip.
In the past, we've had these posted at machines on ball-bead chains for operators to reference. We had groups of about 15 colors (as seen with samples of carpet and other materials... )

This hasn't worked, though - they've fallen apart, the chains stolen on night shifts, etc.

Does anyone have a good idea on how to display these?

I don't know how familiar you are with the vagaries of color evaluation, but the light source can make a big difference in color perception. See Metamerism (color) for example. Molded-in-color plaques also need to be protected from UV and other potential sources of fading.

If you're confident that the plaques are reasonably protected and efficacious, your problem isn't with the plaques, it's with the people who use them.

I was about to point out the same thing about color comparison as Jim did.

Here's my experience in plastic processing:
1) Keep the chips in the lab and leave approved first article parts on the production line for the operators to use... QC still did the comparison to the chip in the lab periodically. This depends on the size of what you're making... we made bottles and closures that didn't take up too much space on the line.

2) Use a color measurement device and be rid of the chips altogether except for a single reference standard in a secure location. This is the most accurate, but also expensive. Those devices aren't cheap. This was in an extrusion plant and QC did the color measurements a few times a shift.

I don't know what your staffing is, but this is what I've done in the past.

The other issue - it does seem that you may have an accountability problem. Who is responsible for the chip and is this person being held accountable? We keep all kinds of gauges and tools on our production lines and they very rarely go missing becuase there will be hell to pay if they do.
At the start of every shift the operator signs on his production sheet that all gauges are at the machine. When some incidences of missing gauges affect a person's review and pay increase you bet they pay attention.

I'd agree with Jim that it is the control of the people using the standards. Depends what industry we’re talking but “items used in the determination of quality need controlled” is not unheard of. It might sound like more work but personally those type items were controlled via the gage system. Calibration can be as simple as “can they find it” and matched to a stored set that doesn’t get wear and tear at some frequency. 1) people take a little more care with gages, 2) it moves responsibility over to the supervisor to be able to find the gages for their area and responsibility. It is monitored if lost or not available and steps to replace already laid out.

The inspection frequency can be very high to start until Production shows they can keep them where they should be. I’d even push that at the start the supervisors are responsible to verify at the start/end of shift that they are there. People only care if they think others care. If mgt is serious that the standards are present and used…they need to show it visibly. Audit and address it until they stick to the program.

Are there Gloss issues involved, or is this just a colour issue?

BTW - A true colour comparison should be made in a MacBeth light booth or in clear sky noon sunlight.

Gretag MacBeth Light booth Calibration (http://elsmar.com/Forums/showthread.php?t=13967)

I used a spectrophotometer in a previous life.