The "Semivowels" or non-syllabic vowels j and w in Old Georgian and in the modern dialects may be evidenced as positional variants of certain vowels and consonants):

w  in Old Georgian was a positional variant of:
a) u in the postposition of a vowel: tku (say, Imperative II) > tkwa (said, Aorist), su (drink, Imperative II) > swa (drank, Aorist)·

b) u (in the interconsonantal position) > w in the position between a consonant and a vowel: k'wets (cuts, is cutting, present) - sa-k'ut-ar-i (own, nominative).

The semivowel w in dialects may be:
a) A positional variant of the labiodental consonant v: bevri > bewri (many), as in the Gurian dialect, rva > rwa (eight), as in Kakhetian, Meskhian).

b) A positional variant of the vowel u, as in akauroba > akawroba "this place" (Meskhetian dialect), uaresi > varesi "worse" (Gurian, Lower Imeretian).

W is evidenced in the labialised on-glide and off-glide of labial vowels in some dialects: ori (two) > wori.

In the Old Georgian alphabet the grapheme expressing the vowel u and in some cases the grapheme expressing the diphthong wi were used to represent w. A special letter for its spelling was used in the 17-18th centuries and was removed from the Georgian alphabet by Ilia Ch'avch'avadze in the 19th century.

J in Old Georgian was a positional variant of i:
a) In the postvocal position in the  case markers of the nouns ending in the vowel in Old Georgian: deda-j, deda-jsa.

b) In the superlative degree of adjectives in Old Georgian: umjobe-js-i, uprojs.

c) In some adverbs: kwemojt, zedajt.

J in dialects may be:
a) A positional variant of a vowel in the postvocal position: deda-i > deda-j (mother. Nominative) (Tushian, Gurian, Atcharian); c'ejghe (you took it away, in Athcarian).

b) A reflex of the fricatives (spirants) in the position V - C or V - #  (the position  between a vowel and a consonant or between a vowel and a pause): gazrdis > gajrdis (he will bring up smb., in Kakhetian).

c) A positional variant of s-(/-h) (the second subject person and the third object person markers, usually in the position between a vowel and a consonant): ga-h-bedav > ga-j-bedav (You will dare),  da-h-baravs  > da-j-baravs (He will dig the ground), e. g.:
rasa hbarav > rasaj barav ("What are you digging?") (in Kartlian, Kakhetian, Pshavian, Mtiulian, and other dialects).

Ilia Ch'avch'avadze removed the grapheme expressing the sound j from the Georgian alphabet in the 19th century.

Tamaz Gamkrelidze and Givi Matchavariani understand j and w (as well as l, m, n, r) to be sonants in the Pre-Kartvelian language (Tamaz Gamkrelidze, Givi Matchavariani, Sonant'ta sist'ema da ablaut'i kartvelur enebshi, The system of sonants and ablaut in the Kartvelian languages, Tbilisi, Mecniereba, 1965)