A commonly used term when it comes to Jaeger-LeCoultre colourful patterned dials is “Lapis dial” or “Scale dial”, dials in blue or brown.
Both exists, but they are not the same!
The earliest trace of these kind of dials I have in my library is from 1967, a small pendulette table clock, and these dials were used at least during the early and mid 1970’s, after that I am not sure.

Lapis dial –
One confusion among collectors is that often “Lapis dial” is used as an expression for any patterned dial regardless of colour, either its blue or brown.
Lapis or Lapis-lazuli which is the full name of the metamorphic rock which gave name to this blue colourful pattern. Lapis-lazuli dials only exist in blue – but, all blue pattern dials are not Lapis dials…
Example, see document below, reference 11012 to the right.

Scale dial –
The “Scale dial” comes from “scale decor”, a term Jaeger-LeCoultre originally used for this pattern, but already back then there was a bit of confusion about the name. Scale refers to the Tortoise shell, the pattern on the shell and not the pattern of scales!
These Tortoise shell dials I suspect existed both in blue and brown.
The biggest differences between the Lapis pattern and the Tortoise shell pattern are that the Lapis pattern is grainier or more like pixels in today’s vocabular, while the tortoise shell pattern is more like smudged areas and the Lapis pattern have lighter “dots” included in the pattern.
Example, see document above, reference 11012 in the middle.
And here are two examples from my collection, Lapis dial and Tortoise shell dial on two Pocket Memovox:

But there was also a brown dial with pattern similar to the Lapis dial…
Porphyry dial –
Porphyry is an igneous rock which is brown. Quite similar to the Lapis in style but brown… And yes, the Porphyry dials only existed in brown.
See document below, reference 531 to the left.

One thing that fascinates about these kinds of dials is that no one is alike. Even within the same type of dial there are big variations. Like in this example from 1971. All three watches have Lapis dials, but all very different blue pattern.

Now, the most famous watch with this kind of patterned dials is the E 855 Memovox.
The only document I have showing the E 855 with patterned dial is this page from the 1970 Jaeger-LeCoultre catalogue:

The document does not name the dial type, but to me this looks like a Tortoise shell dial!
All photos of E 855 Memovox following here are of watches, not belonging to me (unfortunately) but to a dear friend which gave me his permission to share them here – thank you!
As you can see in the document, it is a 18K gold watch with the brown dial, exactly like this one:

Until very recently, my belief was that the gold E 855 only came with the brown Tortoise shell dial.
Previously I have seen some very well make fakes and frankens with yellow gold case and blue Tortoise shell dial. Now another gold/blue dial watch surfaced which looks very correct, but I haven’t had a chance to have a closer look… If that is a correct E 855, it changes the game again…!
What is for sure regarding the blue version dial is that the stainless steel E 855 existed with such blue dial, like this one:

No document, so no indication of what Jaeger-LeCoultre labelled this dial, but to me this looks like another Tortoise shell dial but in blue!
Based on the only document and the fact that these are very seldom encountered, I would say that the number of watches made with these dials was very limited!
My conclusion,
The Lapis dial was used both on clocks and wrist watches but never on the E 855 Memovox.
The Porphyry dial was used on clocks, I never saw on a wrist watch, but let’s not rule it out… A lot of obscure time only men’s and ladies watches existed during the 1970’s with a lot of different dials…
The brown Tortoise shell dial was used on clocks. On wrist watches I only saw the E 855 Memovox.
The blue Tortoise shell dial I only saw on the E 855 Memovox, never on a clock, but would not rule it out that it didn’t exist…
If I am correct, the Tortoise shell dials was only used on the E 855 Memovox and not on any other wrist watch.
Again, BIG thank you to the owner for letting me share his beautiful watches here!

Note:
I) There were actually even more types of “stone pattern” dials, but that would have been a too wide topic for one post.
II) Regarding fake and frankens, I will return in a separate post, as I would not like to stain this absolutely stunning pair of E 855 Memovox with Tortoise shell dials with that!