I have a Nokia 5800 XpressMusic and could not find a suitable for original silicone sleeve. Although it is probably the more common model in the market than the Nokia 5230th But as these two handsets are evidently almost identical, I once ordered this envelope. Result: The cover fits exactly for Nokia 5800 with two restrictions 1) The cut-out for the camera lens covers the flash LEDs (the Nokia 5230 has probably no LEDs). (Night or interior shots) If necessary, you have but the phone quickly pulled from the silicone case. 2) The right stereo speaker is from the sheath concealed while the left is cut out (I guess because the Nokia 5230 has only one mono speaker). The sound is still good to hear troztdem handsfree.
The SIM card slot and the memory card slot are hidden, but I think that that is the case for both models. All other controls are within easy reach, either by recesses or embossed markings on the silicone sleeve.