It is a cut and polished Brazilian agate, appears to be natural color. Many imported are dyed various strange colors, such as blue, green, red, pink, orange, purple, etc.
If you are happy, then it was a good trade. It is not a geode, because by definition a geode is hollow and contains a coating of crystals, commonly quartz. These agates formed from silica..agate..deposited in gas cavities in lava flows.
You can orient your specimen as it formed in the ground, because the horizontal deposits are always on the bottom of the stone, where the silica pooled up as it filled in. The small crystal pocket then at the top of the stone was formed last in the sequence, as the fluids were slowly cut off by the deposition process.