I think maybe Crystal guava from Taiwan is different from Crystal guava from Malaysia or Indonesia. 
Crystal from Malaysia or Indonesia has round leaves.  Crystal Taiwan has normal shaped leaves and is dwarf. 
I think the Crystal from Taiwan is supposed to be tastier and more productive, but is not completely seedless.
Can anyone confirm or refute this?

Yes, many people and some nurseries say they like Taiwan guava the most.  Thailand also gives us many good tropical fruit cultivars, but the Taiwanese farmers and agriculture scientist are very diligent and innovative.  Maybe they spend more in R&D.

No they are all different especially if you like guavas.  Taiwan alone has more than 10 commercially important types of guava.  I'm still waiting to find out which variety my "Taiwan" guava that came from FL is.

Air layering is better for many reasons for most guava varieties, but some guava varieties have very weak roots. 
I think Crystal Seedless might be one variety that grows better on another rootstock than on it's own roots.

I remember meeting the guy who developed the "Tice" mulberry at a CRFG-festival of fruit many years ago and for the life of me I can not remember the alternative name that Tice also goes by but there is another name!!
Any body out there have that other name?
Old fruit brains seem to ferment

Is it Shangri La?  They seem similar in description: large fruit, delicious, big leaves and from Florida.

Looking for B-10 carambola scions.

I'm willing to buy or trade. This is what I have in budwood, but a few are seedlings:
 
Stone fruits - black boy, mid pride, florida prince, eva's pride, tropic snow, santa barbara, august pride, artic star, flavor grenade, splash, emerald drop
Figs - Col de Dame Blanc, Negronne, Desert King, Adriatic JH, Panache, Marseille Black vs
Pomegranates - Parfianka, Ariana, Purple Heart, Desertnyi, Gissarski Rozovyi
Persimmon - giant hanafuyu, fuyu
Apples - fuji, williams pride, tropic sweet, sundowner (cripps red)
Avocado - Mexicola, Day
Loquat - mcbeth, tanaka, argelino, novak, kanko
Mulberry - cooke's pakistan, tice, tehama, shangri la, black beauty, gerardi
Che melonberry
Jujube - sugarcane, shanxi li, sihong, chico, tigertooth, autumn beauty, black sea, taiwan giant(Indian)
Guavas - peruvian, mexican cream, ong, arabian, taiwan, crystal
Pineapple Guava - nazemetz, mammoth, apollo
Star fruit - kari, fwang tung, sri kembangang, bell
White Sapote - vernon, rainbow, malibu #3, walton, redlands
Sapodilla - alano, silas woods, makok
Mango - mallika, carrie, Maha Chanok, duncan, fairchild, pickering, ice cream, amrapali, honey kiss, rosigold
Longan - Kohala, biwe kiew, fortune eye
Jambolan (java plum)
Guabiju
Wampee - Chi Hsin (guy sam / chicken heart), rock candy
Monkey Orange - spiny(Strychnos Spinosa)
Imbe
Mexican Garcinia (Luc's)
Psidium Guineense
Eugenia - Surinam, Pitangatuba, Cherry otRG
Orangeberry (Gin Berry)
Marula - female, male
Guamuchil
Barbados Cherry
Bael fruit

Robert, they're big because of the cluster size. The tree naturally drops most of the fruits leaving a handful or less to ripen in each cluster. The Japanese should grow this so they don't have to manually remove fruits, if you've seen how they grow these and put little "socks" on the few remaining ones.

I have to ask my uncle what color the inside is. The tree belongs to his friend in San Jose. I should be able to ask for scions. My seedling is still a single stick that I put in the ground late last year.

I actually don't have a Big Jim grafted despite it being so common. It's good to have as a standard for comparison. For all we know a lot of the large good loquats could just be Big Jim since it's the one being sold at Home Depot.

Jim has several varieties he grew from seed that were pretty good as well. I only have the
Jazzy and Jim's Big White take despite several years of trying. I hope Mark Lee or someone close to him is helping keep these varieties going. The Jim's Big White tastes pretty good and is white-fleshed. The white fleshed ones go from acidic to sweet as they ripen. I think the taste is better than the orange fleshed ones that don't have much acidity.

I got some fruits from the Avri this year and they're large and orange-fleshed. The mediocre quality could be because it's the first year. They went from watery sweet to fairly sweet as they ripened.

Have you tried the Champagne loquat? I first tasted one from Dennis Sharmahd and it was really good. It's white fleshed. My family thinks it tastes weird because it tastes like pear rather than loquat.

Hi Fang, how did your Avri loquat taste last year 2018?  Same as 2017 or better?
I have an Avri I grafted last year, but I'm think of grafting McBeth or Argelino over it if Avri is just average. 
Did you successfully graft the Tanaka scion I sent you a few years back?  If so how does it compare to the your other loquats?

Read on a couple websites that pink guavas might be slightly more cold hardy than white guavas.  Can anyone confirm or refute this?

I'm also curious about the white Cuban guava that Toptopicals and some nurseries sell.  Does it taste good? How does it compare to other guavas?

I've bought other guavas from toptrop:
Peruvian - sweet soft mediun size fruit, lacks acidity, low seed count, very productive
Barbie Pink - low on flavor and sweetness(probably should have gotten the Ruby Supreme)
Tikal - very productive, low on flavor and sweetness

Mexican Cream - strong sweet smell and taste, small soft fruit, not productive at all.  They seem to like it more in CA where it's cooler.  Maybe Mexican Cream doesn't need as much heat to sweeten up.
White guava from Exotica Nursery in Ca - Steve told me it's seedless and productive, but it turned out to be seeded.  He told me later his guavas are seedlings.  At first I was disappointed until the 3rd year when the large white guavas on this tree became super sweet with some tartness too.  They are super flavorful even when they are still crunchy.  Best damn guava I've ever had is what most people say when they try it.  I'm not sure how much the desert heat and sun here in Phoenix has to do with the fruit quality.  I might be ordinary grown elsewhere.

Strange some of you had imbe trees with shallow or wimpy root systems.  All my imbes had extremely long tap roots when I took them out of pots to plant in the ground.  The tap roots are at least twice as long as the top is tall.  So a 2 foot tall imbe has a 4 foot tap root.  I dug extra deep holes to plant them, yet I still had to coil the tap roots to make them fit in the holes.  They don't however have very many fibrous roots.

My two biggest imbes are 10ft tall, but still no flowers.  They've been in the ground for 3 years and are probably 5 or 6 years old.
Some useful info from my experience is that they:
*survived 25F low with a few 5 gallon buckets of water next to them. Only leaves and small twigs damage.
*can withstand full day summer Phoenix sun and heat, which is impressive.
*grow well in the 8+pH clay soil and hard water here
*have some iron or zinc deficiency like citrus does here.

I know some people have grafted Luc's Mexican and achachairu to imbe.  Did it work and did it grow long term?  Please share your knowledge!

Hi All,
Is Luc's Mexican Garcinia compatible with Imbe rootstock long term?
Does anyone know of a healthy Luc's Mexican Garcinia on Imbe rootstock?

I have two 10ft tall Imbes in the ground that still haven't flowered.  How long do Imbes take to flower?
So I'm thinking of grafting Luc's Garcinia to them. 
I have a 3 year old Luc's seedling that's 10" tall, no kidding.  They grow so slowly here in Phoenix, AZ.
Imbe is the only garcinia that I know of that grows well in our 8+pH clay soil and take the Phoenix sun and summer heat. 
It's also cold hardy down to 25 degrees.
If they are compatible long term, then Luc's would probably be better off on Imbe rootstock than on it's own roots.

Thanks for any info,
Steve

I guess it's not a monkey orange then, but a Monkey Apple.

It looks like some kind of Monkey Orange, in the Strychnos family.  Stychnos Spinosa is from Africa, but Costa Rica has Strychnos species too.  Seeds are usually poisonous...gulp

Hmm that maybe it, there aren't any ripe ones around, but i think the seeds seem viable.