Brilliant cymbals were advertised by 1971. The patent was applied for Feb 6, 1970 granted 3640029 Feb 8, 1972. See: http://black.net.nz/cym2014/z-brilliant.jpg
$8 additional per cymbal and available on Avedis Zildjian and Zilco cymbals. A Zildjian & Cie came after the introduction of Brilliants.
That version of the A Zildjian & Cie stamp is the 1973 one. I haven't yet pinned down when that version was replaced by the later A Zildjian & Cie trademark. The later version has stylistic similarities to the K trademark introduced in 1982 or so, and the A Zildjian & CO. stamp which is also 80s. See: http://black.net.nz/avedis/avedis-gallery.html#AZCieConstan
I don't know where eBay is getting the range of $169 and $299 from. Is that specific to A Zildjian & Cie cymbals? Is that specific to the 1970s? My research shows an expected median value of $120 which is well below their entire range. I don't report them separately (only 5 completed sales for 20" rides so far) but the bigger context on prices is
[img]http://black.net.nz/avedis/images/A20-price-by-era.png[/img]
The A Zildjian & Cie cymbals tend to be heavier (a nice rock ride as you say) and fetch prices with the same distribution as other 70s cymbals. So the median expected price is $144 with half selling for between $88 and $165 n=46.
If the eBay price range is mixing in A Zildjian & Cie Vintage (very different cymbals and very different price behavior as you can see over on the far right) I can see them getting the range they report. One quarter of cymbals offered for sale have either no identification of production era, or an incorrect identification. So if the eBay algorithm doesn't identify the cymbals properly and just uses the seller description you can expect inaccurate results. See: http://black.net.nz/avedis/avedis-prices.html#confusion-matrix
So $60 is great buying, but possibly not as great as that eBay price range suggests. I am really interested in following up precisely where and how that eBay price range is presented.
Note about labels in the graph: T = Trans Stamp, L = Large Stamp, S = Small Stamp, M = Modern (laser stamp 1994 onwards).