Print this out on thin card or laminate your sheet of paper for ease of use. 

Punch a hole in the centre of each shade strip, and then hold it over the yarn you wish to evaluate.

When the hole in the card becomes at its least conspicuous, that is the value of the yarn you are testing. If you find others of similar or close valuations, then your yarns will blend well together.
 

The patterns to be downloaded here are the first four of a number which have been designed as colour sampling exercises to fit in the pockets of a Clippykit display bag. These will be changed for a new set every so often.  You can use them to try out colour juxtapositions, schemes and theories, such as those to be found in Deb Menz’s colorWorks. The threads suitable for the two dot pitches used here are stranded cotton for the wider pitch and cotton pearl 8 for the smaller one, both of which come in wide colour ranges.
 

These are strips taken from the Driftwood panel on page 115 of Contemporary Lace for You.

If you use them to play with colour schemes, you can evaluate your choices without getting distracted too much by the way the threads would work through the lace if you used a geometric pattern.