Might be a more recent origin.
Lot 485: Antique Turkmenistan Silver Ornaments Tribal Jewelry. (3)
Sold: Log in to view, Palmyra Heritage Gallery, December 9, 2018, New York, NY, US
Description: Antique Turkmenistan Silver Ornaments Tribal Jewelry. (3) Size 5 3/4 – 4 1/4 inches length. weight 134.25 grams. Lot of 3 antique Turkmenistan Russian Orthodox Tekke. This antique tribal gilt silver ornaments with stone inset, decorated with ornate design, is a typical Turkomen design. A traditional for women in the Turkmenistan region.
Medium: Antique, Turkmenistan, Silver, Ornaments, Russian, Turkish, persian, Tribal, jewelry,
Another similar piece lists
Tribal Turkmen antique silver pendant. Yomud Turkmen group silver work. Five irregular shape large carnelians stones in the form of amulet against “evil eye”. Three of the stones are in tabel cut form and other two are domed. Double fine wire work frames with corner loops to have dangles.
But the religious affiliation seems "flexible" (note the URL pointing to islamic-central-asia-ornaments):
Antique Turkmen (Turkoman) Yomud Tribe Pendant, Turkmenistan, Central Asia, 50 Grams
This is a collectible early 20th century classic style handcrafted Gol-e kamar (waistband) of the Yomud Tribe from Turkmenia (Turkmenistan) in central Asia.
I have identified the pendant from the last listing photo - detailed as Belt Elements from Turkmen Yomud People, Quai Branly Museum, Paris and this pendant was at one time part of a more elaborate belt.
The diamond shape has a 7mm band border of decorative silver platted wire applied around and a central table cut carnelian in a bezel setting. There is also filigree and applied units.
The back has a bronze border added also extending at the top to form a bale.
There is beautiful wear on this piece, particularly three diamond point which are now rounded. This is a very common sign of wear that you see on many of these type of pieces.
The pendant has been silver tested for approx. 800 (80% silver or 800/1000).
I have not polished the pendant as it has the lovely worn patina but will polish up beautifully.
Width: 7.5 cm (3")
Height: 11.5 cm (4 1/2")
Weight: 50 Grams (1.765 oz.)
Pendant Tested: 80% Silver approx.
Turkmen Chain: 48 cm (19") 92.5% Sterling Silver
While one auction mentions the "Tecke" (French Wikipedia) and "Russian Orthodox"
A 2009 Pew Research Center report indicates a higher percentage of Muslims with 93.1% of Turkmenistan's population adhering to Islam.
Personally, I deduce from this the probability that the shape we see is cross like, but more geometry than Christianity. But trusting the auctioners from the first link this is perhaps from the 10 remaining percent of the population there: "Turkmenistan Russian Orthodox Tekke".
Things to consider for that: while there is a certain cross shape, this is really neither a proper Latin, nor a Greek, nor an Russian (Orthodox) cross.
If it is Tekke, then it was to be worn in this style:
via Turkmen jewelry (source)
Metropolitan Museum on Turkmen jewelry gives some of the keys to making finding this easier:
In addition to the shape and theme of the silver metal itself, the semi-precious stones that embellish the jewelry are also imbued with protective powers. Pieces of carnelian, a bright red colored stone, are popular because they are believed to protect the wearers from illness and death (2006.544.13a).