I used the stylus balance that came with my new E.A.T C-Major turntable first. It's the exact same piece of plastic with a strip of metal that came with my Pro-Ject RPM-1. It doesn't have a line at 2.3grams, so I extrapolated between 2 grams and 2.5. When I got the new unit (with calibration weights), I found I was actually running at 2.7 grams, so I'm much more confident with the new one, and $28 wasn't hard to come by.
Your avatar photo is way too small for me to see any detail of what you use.
Oh! Yeah, calibration weights are a whole different story, and I don't have any weights in that low range. I did not calibrate my balance, took it for granted that it was accurate, which is an easy mistake to make. But, my players track just fine so I"m pretty confident that it's good enough. But, yeah, yours was worth a few extra $ just to get the weights with it.
Hopefully you know this, but you should ONLY handle the calibration weights with gloves or lab glass wipes (Kem-Wipes). Oils from your skin will get on the weights and change the mass of the weight, so then you will start getting inaccurate calibrations.
I have this one, but I paid only about $23 for it, and it has much better resolution than what yours did.
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EDIT-- I see now, the low weight that came with it was 5g, I would rec picking up a weight closer to the range of your actual measurement for the best accuracy. I know 1g are readily available, not sure about other weights between 1-5g.