Semicolon as a super-comma preceding “etc.”

I was wondering which punctuation to use preceeding etc. in an enumeration with semicolons as supercommas (as formulated here: http://theoatmeal.com/comics/semicolon).

People with dichromatic colour vision will usually find it difficult to distinguish between similar tones and shades: deep red with black with dark green or dark purple; medium shades of red with similar tones of green and orange; etc.

Should I use a semicolon or a comma before the etc.?

Solution 1:

This is a simple list of 3 elements, not a complex list of 2 elements whose second element contains two subelements.

Case 1

1. deep red with black with dark green or dark purple
2. medium shades of red with similar tones of green and orange;
3. etc.

Case 2

1. deep red with black with dark green or dark purple
2. medium shades of red with similar tones of
   1. green
   2. orange
   3. etc.

The semicolons make it clearer that case #1 applies than would the comma.

Contrast:

• People with dichromatic colour vision will usually find it difficult to distinguish between similar tones and shades: deep red with black with dark green or dark purple; medium shades of red with similar tones of green and orange; etc.

• People with dichromatic colour vision will usually find it difficult to distinguish between similar tones and shades: deep red with black with dark green or dark purple, medium shades of red with similar tones of green and orange, etc.

In the second version, it is far from immediately obvious that we are not talking tones of green, orange, and others. Using the semicolon makes this clear(er).