Considering Sona's ablity to buff her AAs for good poke and engage, would IBG be a good item for her? Sure it scales of physical damage, but the utility and all of the stats are beneficial to Sona.
Iceborn Gauntlet is actually a very nice pick on Sona. While on support Sona, you may pick it up as a luxury item and ONLY if you're winning. This will increase the amount of dominance that you have within the game, but I wouldn't recommend it if you are losing. It's too expensive, and it's more beneficial to build Mikael's Blessing and Locket of the Iron Solari to help give some help in teamfights.
However, recently, top lane Sona has become a bit of a thing. Top lane Sona is ridiculously irritating due to how strong Power Chord damage is, as well as the ridiculous sustain Sona naturally has. To couple this irritating poke is your Iceborn Gauntlet, and the armour gives you more effective health. Not only do your basic attacks and spells have increased damage, but the slow is ridiculously irritating. Couple this with a tankier build, and you have one very irritating Sona. It also synergises well with the spammy nature of Sona.
If you do want to try out top lane Sona, then be sure to build this. It's worth a try.
It's a nice pick. It brings you everything you need and on top of that has a really sweet passive that increase the amount of crowd control you can bring.
But be careful. Compare to other items: it has a very high price.
I consider it has a viable/situational item on Sona, but I would'nt recommand it due to the limited income you have. If you need some armor/cooldown reduction Frozen Heart and Ohmwrecker would be more valuable: better utility, fits more your stats, cost less.
If you are talking about support Sona, then you should never build Iceborn Gauntlet as there are way too many other items that you have must get and even if you had lots of gold to spare, there are better luxury items for support Sona.
As for lane Sona... I suppose it could be a situational pick up, but most of the time, you'd be better off just getting a Lich Bane and stacking AP.
Its a risky item but it can be worth it for the CC. The problem is how squishy Sona is so if you try and autoattack you can get caught out and killed if you arent careful. If you build a tank item or 2 such as ROA you will usually be safe though.
I'm backing Starstalker on this one, it's a good pick, but you need to spare a lot of gold and there are other items that could be more benefitial for a support Sona. Lane Sona (perhaps mid lane) sounds weird, but IBG would definitly work on she.
However, recently, top lane Sona has become a bit of a thing. Top lane Sona is ridiculously irritating due to how strong Power Chord damage is, as well as the ridiculous sustain Sona naturally has. To couple this irritating poke is your Iceborn Gauntlet, and the armour gives you more effective health. Not only do your basic attacks and spells have increased damage, but the slow is ridiculously irritating. Couple this with a tankier build, and you have one very irritating Sona. It also synergises well with the spammy nature of Sona.
If you do want to try out top lane Sona, then be sure to build this. It's worth a try.
But be careful. Compare to other items: it has a very high price.
I consider it has a viable/situational item on Sona, but I would'nt recommand it due to the limited income you have. If you need some armor/cooldown reduction Frozen Heart and Ohmwrecker would be more valuable: better utility, fits more your stats, cost less.
As for lane Sona... I suppose it could be a situational pick up, but most of the time, you'd be better off just getting a Lich Bane and stacking AP.