Smooth chocolate can be Jain-friendly, but only under some clear conditions:

1. Ingredients must be fully veg

- No eggs, egg powder - No gelatin, no animal fat - No honey - Many Jains accept milk; strict/vegan Jains avoid milk, whey, milk powder etc.

1. Prefer simple dark/plain chocolate

- Just cocoa, sugar, cocoa butter, permitted emulsifier (veg source), and natural flavours. - Avoid chocolates with marshmallows, jelly, or unknown additives.

1. Check for hidden non‑veg items

- Gelatin, certain E‑numbers (like non‑veg E471/E472), carmine (insect colour), alcohol‑based flavours.

1. Paryushan / Chaturmas / special vows

- During Paryushan/Das‑Lakshan or if you have taken any extra niyam (vow), most gurus advise avoiding chocolate and all such processed tasty items, even if technically veg.

1. Digambar / Shvetambar

- There is no separate rule about chocolate by sect. - Both focus on ahimsa, simplicity, and following your own pachchakkhan (personal vow).

So:

• For normal days: smooth chocolate can be viable for Jains if it is completely vegetarian (and matches your dairy/vegan preference) and you read the ingredients carefully.
• For periods of tapa (Paryushan, Das‑Lakshan) or if you follow stricter ahimsa, it is better to avoid chocolate altogether.

You can see a related explanation here