Yes, it's never pronounced as J.
In literary Russian norm Г is
1. /g/
2. palatalized ('softened') /g'/ before е-ё-и-ю-я - as in geology
- the process analogous to its changing into J before e-i-y in English and Romance languages.
3. /v/ in the ending -ого -его (красного, его, чего)
4. /k/ in the word-final position. All Russian consonants become voiceless in this position.
5. /х/ in the word-final position in some exceptions, the most famous being Бог -God. /Бох/. Don't sure if there're other 'exceptions', BTW...:)
I have an impression that a couple of other similar words with _facultative_ /-x/ pronunciation exist, but in Бог it's close to obligatory: pronouncing /бок/ one will be misunderstood as saying 'бок'
5.1 There exist facultative pronunciation /Боɣ/ (voiced counterpart of /х/). It's acceptable even though the phoneme 'doesn't exist' in Russian:) It may arise in some other words: /ɣ/осподь, бо/ɣ/тый.
6. /к/ before other voiceless consonant: ногти (-kt-). all Russian consonants become voiceless in this position.
7. /x/ in лёгкий, мягкий, легче, мягче (_native_ Russian words before к/ч.) and may be in some similar words (but I can't remember other examples, so maybe they don't exist).
This list may be non-comprehensive. I wrote it by memory.
8,9: in some _dialects_ of Russian (south and south-west) they say [ɣ] or [ɦ] etc. instead of /g/.
Most of Russian speakers confuse these sounds and call them 'Ukrainian G' (pronounced 'украинское ɣэ', as Russians have NO problems with pronouncing /ɣ/ and) or /ɣэканье/ 'ɣeking' (there're no proper way to write it:) no letter for ɣ-sound) - and it doesn't matter if the sound is [ɣ] or [ɦ] and does ut comes from Ukraine or Belarus or the Russia proper:)