Eusideroxylon zwageri (Bornean Ironwood) Chopsticks

This is sort of a continuation of this blogpost, in which detailed my visit to the SBG's Ethnobotany Garden where I saw a medicinal pounder made of Belian wood: http://openplants.blogspot.com/2019/07/sbgs-bird-attracting-tree-and-new.html

Belian wood is another name for Borneon Ironwood, and it was written on the pounder's signage that "it is weather-proof and made to last for centuries even with outdoor use". Made me want to get some Belian wood myself. So I went online shopping and found the most inexpensive type to be chopsticks. One listing said that the chopsticks were "made of premium Bornean ironwood (Eusideroxylon zwageri)", but are they really?

This is one of the photos posted on that Amazon listing of Natural Iron Wood Chopsticks. Note the vascular bundle like spots at the cross section (top of chopsticks).

But what has vascular bundles? That's right, monocots like bamboo. Bamboo is commonly made into reusable and disposable chopsticks.

Then I went on to an online hardware shop that sells Belian wood planks. Given the price and that the physical store was located in Malaysia, I suppose the wood was authentic. The cross section of the wood also has spots. Could they be ray cells?

So how could chopsticks be reliably be determined to be made of some kind of dicot wood and not bamboo? Are the only reliable ways be to: 1. Buy the wood from a trusted source and make the chopsticks myself, or 2. Send the chopsticks to a wood anatomy expert?

Another listing of natural wood chopsticks stated that before first use, they should be soaked in cold water with a pinch of salt added for 4-6 hours, then wiped with vegetable oil after drying. The listing noted that water in which the chopsticks were placed in would change colour. The browning could be caused by tannin that is present in bark, wood, leaves, etc., to help the tree protect against predation and infection by bacteria or fungi.

Could Borean Ironwood or any other hardwood be reliably used as chopsticks "for decades" when they are constantly washed, touching hot food and placed into mouths?

Browning of water that could be caused tannin seeping out of the wood. Not dyes or paints as some buyers suspected.

Bamboo wood is a thing.

Small pits observed at the cross section of a pair of chopsticks that I found in a random drawer.

Supposedly made in Japan or made for the Japan market, and if I understand the kanji correctly, part of it reads "natural wood".

Looked like it was heavily dyed and lacquered.

Another pair of chopsticks that I received as a souvenir from Japan, which have no small pits observed at the cross section.

Looked like it was dyed but lightly lacquered. Overall it feels better made than the previous chopsticks.