Gretsch Guitar Fret Markers
Prior to 1957, Gretsch was unpredictable, putting several different kinds of fret markers on their guitars. Generally speaking, and not counting lower line guitars, either "humped block" or block inlays were found on mid- to upper-line models prior to '57, but there was substantial variation in styles.
Some models, like the Super 400 Synchromatic, had intricate gold, black and white inlays within the block markers. Later, fancy engraved markers decorated mid-'50s White Falcons and Chet Atkins models. Lower-line guitars used dot markers.
In the electric post-war era, as Gretsch began to solidify their line-up, plain block markers became the general standard on mid- to upper-line guitars. Engraving began to disappear from all but a few models, and the differentiation was simple; dot markers for the entry level, block markers for everything else.
Cow and cactus
Western models featured special block markers with cacti, steer heads and other cowboy-themed engraving.
Starting in 1958, almost all models switched to the "Neo-Classic" markers, also called "thumbnail" or "half moon" markers, and these remained fairly standard through the '60s and '70s on most models. Again, bargain models used simple dot markers.
T-Zone Tempered Treble
Models made in the late '60s and early '70s with the "T-Zone Tempered Treble System" will have dot markers on the highest frets, offset toward the treble side of the fretboard, combined with Neo-Classic markers along the bass side of the fretboard.
In late 1956 a one-year switch was made to "humped-block" markers, which until then had only been seen on a handul of Gretsch guitars, usually near the top of the model range. Because almost all '57 Gretsch guitars have the humped block markers, they're one of the easiest ways to identify '57s.
However, be warned that not only do humped blocks turn up on some pre-'57 guitars, but they're also occasionally seen on some very early '58s. To further complicate matters, lower-priced guitars such as Clippers continued to use dot markers every year.
Plain, simple dot markers were sometimes used on Gretsch's economy-priced guitars.
Bird-themed engraved blocks
Used only on the White Falcon and White Penguin, these block markers featured avian engravings.
Block with inlaid gold sparkle
High-end Synchromatic archtops featured inlaid gold sparkle in thier block markers.
Small square triplets
Originally intended to resemble dice, these unusual fretboard inlays were used on the Atkins Axe and Super Axe models.
Les Paul-style tapered block markers.
Split Humped Blocks
Used on some modern Synchromatic archtops.
A few Gretsches, notably early Americana models, had no fret markers at all.